An original Thinka practice paper modelled on the structure and difficulty of the Nov 2023 (V3) Cambridge IGCSE Mathematics - Additional (0606) paper. Not affiliated with or reproduced from Cambridge.
Paper 13
Answer all questions. Show all necessary working clearly.
12 题目 · 79 分
题目 1 · Short Answer
4 分
Solve the inequality \(|3x + 2| < |x - 4|\).
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解题
Square both sides of the inequality: \((3x + 2)^2 < (x - 4)^2\)
The critical values are \(x = -3\) and \(x = \frac{1}{2}\).
Since the quadratic expression must be less than zero, the solution range lies between the critical values: \(-3 < x < \frac{1}{2}\).
评分标准
**M1** for squaring both sides and expanding correctly to obtain a 3-term quadratic. **A1** for obtaining the correct quadratic \(2x^2 + 5x - 3 < 0\) (or any equivalent form). **B1** for finding both critical values \(x = -3\) and \(x = \frac{1}{2}\). **A1** for the correct final inequality range \(-3 < x < \frac{1}{2}\).
题目 2 · Short Answer
5 分
The polynomial \(P(x) = x^3 + ax^2 - 7x + b\) has a factor of \(x - 2\). When \(P(x)\) is divided by \(x + 1\), the remainder is \(-9\). Find the value of \(a\) and of \(b\).
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解题
Apply the Factor Theorem: Since \(x - 2\) is a factor of \(P(x)\), we have \(P(2) = 0\). \(P(2) = (2)^3 + a(2)^2 - 7(2) + b = 0\) \(8 + 4a - 14 + b = 0 \implies 4a + b = 6\) (Equation 1)
Apply the Remainder Theorem: When \(P(x)\) is divided by \(x + 1\), the remainder is \(-9\), so \(P(-1) = -9\). \(P(-1) = (-1)^3 + a(-1)^2 - 7(-1) + b = -9\) \(-1 + a + 7 + b = -9 \implies a + b = -15\) (Equation 2)
Subtract Equation 2 from Equation 1: \((4a + b) - (a + b) = 6 - (-15)\) \(3a = 21 \implies a = 7\)
Substitute \(a = 7\) back into Equation 2: \(7 + b = -15 \implies b = -22\).
评分标准
**M1** for applying the Factor Theorem \(P(2) = 0\) to form a linear equation in \(a\) and \(b\). **A1** for obtaining the simplified equation \(4a + b = 6\) (or equivalent). **M1** for applying the Remainder Theorem \(P(-1) = -9\) to form a second linear equation in \(a\) and \(b\). **A1** for obtaining the simplified equation \(a + b = -15\) (or equivalent). **A1** for correctly solving the simultaneous equations to find \(a = 7\) and \(b = -22\).
题目 3 · Short Answer
4 分
The position vector of a point \(A\) relative to an origin \(O\) is \(2\mathbf{i} - 3\mathbf{j}\) and the position vector of \(B\) is \(10\mathbf{i} + 12\mathbf{j}\). Find the unit vector in the direction of \(\overrightarrow{AB}\).
Next, calculate the magnitude of \(\overrightarrow{AB}\): \(|\overrightarrow{AB}| = \sqrt{8^2 + 15^2} = \sqrt{64 + 225} = \sqrt{289} = 17\)
Finally, construct the unit vector in the direction of \(\overrightarrow{AB}\): \(\hat{u} = \frac{\overrightarrow{AB}}{|\overrightarrow{AB}|} = \frac{8\mathbf{i} + 15\mathbf{j}}{17} = \frac{8}{17}\mathbf{i} + \frac{15}{17}\mathbf{j}\).
评分标准
**M1** for an attempt to find \(\overrightarrow{AB}\) by subtracting the position vector of \(A\) from \(B\). **A1** for obtaining \(\overrightarrow{AB} = 8\mathbf{i} + 15\mathbf{j}\). **M1** for correctly calculating the magnitude of their vector to be 17. **A1** for the correct unit vector \(\frac{8}{17}\mathbf{i} + \frac{15}{17}\mathbf{j}\) (or equivalent column vector notation).
题目 4 · Short Answer
5 分
Solve the equation \(\log_3(5x - 2) - 2\log_3 x = 1\).
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解题
First, apply the power law of logarithms to the second term: \(\log_3(5x - 2) - \log_3(x^2) = 1\)
Next, apply the division law of logarithms to combine the terms on the left-hand side: \(\log_3\left(\frac{5x - 2}{x^2}\right) = 1\)
Convert the equation from logarithmic to exponential form: \(\frac{5x - 2}{x^2} = 3^1\)
Multiply both sides by \(x^2\) and rearrange to form a quadratic equation: \(5x - 2 = 3x^2\) \(3x^2 - 5x + 2 = 0\)
Factorise the quadratic equation: \((3x - 2)(x - 1) = 0\) This yields two possible values: \(x = 1\) or \(x = \frac{2}{3}\).
Check for validity against the constraints of original logarithm terms (i.e. \(5x - 2 > 0\) and \(x > 0\)): For \(x = 1\): \(5(1) - 2 = 3 > 0\) and \(1 > 0\) (valid). For \(x = \frac{2}{3}\): \(5(\frac{2}{3}) - 2 = \frac{4}{3} > 0\) and \( \frac{2}{3} > 0\) (valid).
Hence, the solutions are \(x = 1\) and \(x = \frac{2}{3}\).
评分标准
**M1** for applying the power law to obtain \(\log_3(x^2)\). **M1** for applying the division law to write the left-hand side as a single logarithm. **M1** for converting the logarithmic equation correctly into exponential form. **A1** for obtaining the correct quadratic equation \(3x^2 - 5x + 2 = 0\) and solving it to find both values. **A1** for confirming both answers are valid by checking domain restrictions.
题目 5 · Short Answer
4 分
Solve the equation \(2\cos^2 \theta + \sin \theta - 1 = 0\) for \(0^\circ \le \theta \le 360^\circ\).
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解题
Use the Pythagorean identity \(\cos^2 \theta = 1 - \sin^2 \theta\) to rewrite the equation in terms of \(\sin \theta\): \(2(1 - \sin^2 \theta) + \sin \theta - 1 = 0\) \(2 - 2\sin^2 \theta + \sin \theta - 1 = 0\) \(-2\sin^2 \theta + \sin \theta + 1 = 0\)
Multiply by \(-1\) to make the leading coefficient positive: \(2\sin^2 \theta - \sin \theta - 1 = 0\)
Factorise the quadratic in terms of \(\sin \theta\): \((2\sin \theta + 1)(\sin \theta - 1) = 0\)
This gives two scenarios: 1) \(\sin \theta = 1\) 2) \(\sin \theta = -\frac{1}{2}\)
Solve each within the interval \(0^\circ \le \theta \le 360^\circ\): - From \(\sin \theta = 1\): \(\theta = 90^\circ\)
- From \(\sin \theta = -\frac{1}{2}\): The reference angle in the first quadrant is \(30^\circ\). Sine is negative in Quadrants III and IV: Quadrant III: \(\theta = 180^\circ + 30^\circ = 210^\circ\) Quadrant IV: \(\theta = 360^\circ - 30^\circ = 330^\circ\)
Thus, the solutions are \(\theta = 90^\circ, 210^\circ, 330^\circ\).
评分标准
**M1** for using \(\cos^2 \theta = 1 - \sin^2 \theta\) to formulate a quadratic equation purely in terms of \(\sin \theta\). **A1** for the correct simplified quadratic equation \(2\sin^2 \theta - \sin \theta - 1 = 0\). **M1** for solving the quadratic equation to find \(\sin \theta = 1\) and \(\sin \theta = -\frac{1}{2}\). **A1** for identifying all three correct angles \(90^\circ, 210^\circ, 330^\circ\) with no extra angles in the range.
题目 6 · Short Answer
5 分
A curve has equation \(y = \frac{e^{2x}}{3x + 1}\) for \(x > -\frac{1}{3}\). Find the exact \(x\)-coordinate of the stationary point on the curve.
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解题
To find the stationary point, we must differentiate \(y\) with respect to \(x\) and set \(\frac{dy}{dx} = 0\).
Apply the quotient rule, where \(u = e^{2x}\) and \(v = 3x + 1\): \(\frac{du}{dx} = 2e^{2x}\) \(\frac{dv}{dx} = 3\)
Using the quotient rule formula \(\frac{dy}{dx} = \frac{v\frac{du}{dx} - u\frac{dv}{dx}}{v^2}\): \(\frac{dy}{dx} = \frac{(3x + 1)(2e^{2x}) - (e^{2x})(3)}{(3x + 1)^2}\)
Set \(\frac{dy}{dx} = 0\) to find the stationary point: \(\frac{e^{2x}(6x - 1)}{(3x + 1)^2} = 0\)
Since \(e^{2x} > 0\) for all real values of \(x\), we solve: \(6x - 1 = 0 \implies x = \frac{1}{6}\)
This value of \(x\) is in the domain \(x > -\frac{1}{3}\), so the exact \(x\)-coordinate of the stationary point is \(x = \frac{1}{6}\).
评分标准
**M1** for attempting to apply the quotient rule (or product rule with negative exponent). **A1** for obtaining the correct derivative of \(e^{2x}\) as \(2e^{2x}\). **A1** for the correct unsimplified expression of \(\frac{dy}{dx}\). **M1** for setting \(\frac{dy}{dx} = 0\) and attempting to solve for \(x\). **A1** for the correct exact value \(x = \frac{1}{6}\).
题目 7 · Structured
8 分
(a) On the axes, sketch the graphs of \( y = |3x - 4| \) and \( y = x + 2 \), stating the coordinates of the points where the graphs meet the coordinate axes.
(b) Solve the inequality \( |3x - 4| > x + 2 \).
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解题
(a) For the modulus graph \( y = |3x - 4| \): - It is a V-shaped graph with vertex on the positive \( x \)-axis. - The vertex is at \( (\frac{4}{3}, 0) \). - The \( y \)-intercept is at \( (0, 4) \).
For the line \( y = x + 2 \): - It is a straight line passing through \( (0, 2) \) and \( (-2, 0) \). - The sketch shows two intersection points in the first quadrant.
(b) To solve \( |3x - 4| > x + 2 \), we first find the critical values by solving the equation: \( |3x - 4| = x + 2 \)
Case 1: \( 3x - 4 = x + 2 \implies 2x = 6 \implies x = 3 \) Case 2: \( -(3x - 4) = x + 2 \implies -3x + 4 = x + 2 \implies 4x = 2 \implies x = 0.5 \)
By comparing the graphs or checking regions, the solution to the inequality is \( x < 0.5 \) or \( x > 3 \).
评分标准
(a) - **B1**: Correct V-shaped graph for \( y = |3x - 4| \) with vertex on the positive \( x \)-axis. - **B1**: Vertex marked at \( (4/3, 0) \) and \( y \)-intercept at \( (0, 4) \). - **B1**: Straight line for \( y = x + 2 \) passing through \( (0, 2) \) and \( (-2, 0) \) with positive gradient. - **B1**: Correct intersection points shown in the first quadrant.
(b) - **M1**: Attempt to solve the equation \( |3x - 4| = x + 2 \) by squaring or using two cases. - **A1**: Finding critical value \( x = 3 \). - **A1**: Finding critical value \( x = 0.5 \). - **A1**: Correct inequality range: \( x < 0.5 \) or \( x > 3 \) (or equivalent).
题目 8 · Structured
9 分
A curve has the equation \( y = (2x - 3)e^{-x^2} \).
(a) Find \( \frac{\mathrm{d}y}{\mathrm{d}x} \).
(b) Find the exact coordinates of the stationary points on the curve.
(c) Determine the nature of the stationary point with the positive \( x \)-coordinate.
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解题
(a) Using the product rule with \( u = 2x - 3 \) and \( v = e^{-x^2} \): \( \frac{\mathrm{d}u}{\mathrm{d}x} = 2 \) and \( \frac{\mathrm{d}v}{\mathrm{d}x} = -2x e^{-x^2} \) \( \frac{\mathrm{d}y}{\mathrm{d}x} = 2e^{-x^2} + (2x - 3)(-2x e^{-x^2}) \) \( \frac{\mathrm{d}y}{\mathrm{d}x} = 2e^{-x^2}(1 + 3x - 2x^2) \)
(b) For stationary points, set \( \frac{\mathrm{d}y}{\mathrm{d}x} = 0 \): \( 2x^2 - 3x - 1 = 0 \) Using the quadratic formula: \( x = \frac{3 \pm \sqrt{(-3)^2 - 4(2)(-1)}}{2(2)} = \frac{3 \pm \sqrt{17}}{4} \)
For the corresponding \( y \)-coordinates: At \( x = \frac{3+\sqrt{17}}{4} \), we have \( 2x - 3 = \frac{\sqrt{17}-3}{2} \). \( y = \frac{\sqrt{17}-3}{2} e^{-\left(\frac{3+\sqrt{17}}{4}\right)^2} = \frac{\sqrt{17}-3}{2} e^{-\frac{13+3\sqrt{17}}{8}} \)
At \( x = \frac{3-\sqrt{17}}{4} \), we have \( 2x - 3 = \frac{-\sqrt{17}-3}{2} \). \( y = -\frac{\sqrt{17}+3}{2} e^{-\left(\frac{3-\sqrt{17}}{4}\right)^2} = -\frac{\sqrt{17}+3}{2} e^{-\frac{13-3\sqrt{17}}{8}} \)
(c) To determine the nature of the positive stationary point at \( x_1 = \frac{3+\sqrt{17}}{4} \approx 1.78 \): We differentiate \( \frac{\mathrm{d}y}{\mathrm{d}x} = 2e^{-x^2}(1 + 3x - 2x^2) \): \( \frac{\mathrm{d}^2y}{\mathrm{d}x^2} = -4x e^{-x^2}(1 + 3x - 2x^2) + 2e^{-x^2}(3 - 4x) \) Since \( 1 + 3x_1 - 2x_1^2 = 0 \) at the stationary point: \( \frac{\mathrm{d}^2y}{\mathrm{d}x^2} = 2e^{-x_1^2}(3 - 4x_1) \) Since \( x_1 \approx 1.78 \), the term \( 3 - 4x_1 < 0 \), meaning \( \frac{\mathrm{d}^2y}{\mathrm{d}x^2} < 0 \). Thus, the stationary point is a local maximum.
评分标准
(a) - **M1**: Attempt to use the product rule to differentiate \( y = (2x - 3)e^{-x^2} \). - **A1**: Correct differentiation of \( e^{-x^2} \) to get \( -2x e^{-x^2} \). - **A1**: Fully correct expression for \( \frac{\mathrm{d}y}{\mathrm{d}x} = 2e^{-x^2}(1 + 3x - 2x^2) \).
(b) - **M1**: Setting their derivative to 0 to obtain a quadratic equation in \( x \). - **A1**: Finding exact \( x \)-coordinates: \( x = \frac{3 \pm \sqrt{17}}{4} \). - **M1**: Substituting at least one of their \( x \)-values back into the curve equation to find \( y \). - **A1**: Finding exact coordinate pairs: \( (\frac{3+\sqrt{17}}{4}, \frac{\sqrt{17}-3}{2} e^{-\frac{13+3\sqrt{17}}{8}}) \) and \( (\frac{3-\sqrt{17}}{4}, -\frac{\sqrt{17}+3}{2} e^{-\frac{13-3\sqrt{17}}{8}}) \).
(c) - **M1**: Finding an expression for the second derivative or testing the gradient on either side of the stationary point. - **A1**: Valid reasoning showing \( \frac{\mathrm{d}^2y}{\mathrm{d}x^2} < 0 \) and concluding it is a maximum.
题目 9 · Structured
9 分
(a) Show that \( \frac{\cos \theta}{1 - \sin \theta} - \frac{\cos \theta}{1 + \sin \theta} = 2\tan \theta \).
(b) Substituting \( \theta = 2x - \frac{\pi}{4} \), the equation simplifies using part (a) to: \( 2\tan(2x - \frac{\pi}{4}) = 2 \implies \tan(2x - \frac{\pi}{4}) = 1 \).
For \( 0 < x < \pi \), we have the interval: \( -\frac{\pi}{4} < 2x - \frac{\pi}{4} < \frac{7\pi}{4} \).
In this interval, \( 2x - \frac{\pi}{4} = \frac{\pi}{4} \) or \( 2x - \frac{\pi}{4} = \frac{5\pi}{4} \).
Solving for \( x \): 1) \( 2x = \frac{\pi}{2} \implies x = \frac{\pi}{4} \) 2) \( 2x = \frac{3\pi}{2} \implies x = \frac{3\pi}{4} \)
评分标准
(a) - **M1**: Putting LHS over a common denominator \( (1 - \sin\theta)(1 + \sin\theta) \). - **A1**: Correct numerator expansion: \( 2\cos\theta\sin\theta \). - **M1**: Using \( 1 - \sin^2\theta = \cos^2\theta \) to simplify denominator. - **A1**: Completed proof showing the steps leading to \( 2\tan\theta \).
(b) - **M1**: Recognizing identity and simplifying equation to \( \tan(2x - \frac{\pi}{4}) = 1 \). - **M1**: Finding first correct value: \( 2x - \frac{\pi}{4} = \frac{\pi}{4} \). - **A1**: Finding \( x = \frac{\pi}{4} \). - **M1**: Finding second correct value: \( 2x - \frac{\pi}{4} = \frac{5\pi}{4} \). - **A1**: Finding \( x = \frac{3\pi}{4} \) and no other values.
题目 10 · Structured
9 分
A sector \( OAB \) of a circle with centre \( O \) and radius \( r \text{ cm} \) has an angle of \( \theta \) radians. The perimeter of the sector is \( 40\text{ cm} \) and its area is \( 75\text{ cm}^2 \).
(a) Find the possible values of \( r \) and the corresponding values of \( \theta \).
(b) For the larger value of \( r \), find the area of the segment cut off by the chord \( AB \).
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解题
(a) The perimeter of the sector is given by: \( P = 2r + r\theta = 40 \implies r\theta = 40 - 2r \implies \theta = \frac{40 - 2r}{r} \)
The area of the sector is given by: \( A = \frac{1}{2}r^2\theta = 75 \)
Thus, the possible values of \( r \) are \( r = 15 \) or \( r = 5 \).
Finding the corresponding values of \( \theta \): - If \( r = 15 \), \( \theta = \frac{40 - 30}{15} = \frac{2}{3} \) radians. - If \( r = 5 \), \( \theta = \frac{40 - 10}{5} = 6 \) radians. Both values of \( \theta \) are in the valid range \( (0, 2\pi) \).
(b) For the larger value of \( r = 15 \), the angle \( \theta = \frac{2}{3} \). The area of the segment is: \( A_{\text{segment}} = \frac{1}{2}r^2(\theta - \sin\theta) = \frac{1}{2}(15)^2\left(\frac{2}{3} - \sin\left(\frac{2}{3}\right)\right) \)
(a) - **B1**: Writing down correct formula equations for perimeter and area. - **M1**: Eliminating \( \theta \) to form a quadratic equation in \( r \). - **A1**: Showing \( r^2 - 20r + 75 = 0 \). - **A1**: Finding \( r = 5 \) and \( r = 15 \). - **M1**: Substituting \( r \) back to find \( \theta \). - **A1**: Finding correct pairs: \( (15, 2/3) \) and \( (5, 6) \).
(b) - **M1**: Using correct segment area formula: \( \frac{1}{2}r^2(\theta - \sin\theta) \) with \( r = 15 \) and \( \theta = 2/3 \). - **M1**: Evaluating \( \sin(2/3) \approx 0.618 \). - **A1**: Correctly obtaining \( 5.43\text{ cm}^2 \) (allow 5.43 to 5.44).
题目 11 · Structured
8 分
(a) A team of 5 people is to be chosen from a group of 6 men and 5 women. Find the number of different teams that can be chosen if the team must contain more women than men.
(b) 7-letter arrangements are to be made using the letters of the word \( \text{ALGEBRA} \). Find the number of different arrangements that can be made if: (i) there are no restrictions, (ii) the two \( \text{A} \text{s} \) must not be next to each other.
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解题
(a) The team of 5 must contain more women than men. Possible scenarios: - 3 women and 2 men: \( \binom{5}{3} \times \binom{6}{2} = 10 \times 15 = 150 \) ways - 4 women and 1 man: \( \binom{5}{4} \times \binom{6}{1} = 5 \times 6 = 30 \) ways - 5 women and 0 men: \( \binom{5}{5} \times \binom{6}{0} = 1 \times 1 = 1 \) way
Total ways = \( 150 + 30 + 1 = 181 \).
(b) The letters in \( \text{ALGEBRA} \) are A, L, G, E, B, R, A. There are 7 letters: 2 A's, and 1 of L, G, E, B, R. (i) No restrictions: \( \frac{7!}{2!} = 2520 \).
(ii) A's not together: Total arrangements - Arrangements where A's are together. Treating "AA" as a single block, we arrange 6 entities (AA, L, G, E, B, R): \( 6! = 720 \).
Arrangements with A's not together: \( 2520 - 720 = 1800 \).
评分标准
(a) - **M1**: Identifying the 3 distinct cases of (3W, 2M), (4W, 1M), and (5W, 0M). - **M1**: Calculating combination products for at least one case correctly. - **A1**: Finding valid counts: 150, 30, 1. - **A1**: Summing to find the correct total of 181.
(b)(i) - **M1**: Showing division by 2! to adjust for the two repeated A's. - **A1**: Finding 2520.
(b)(ii) - **M1**: Finding arrangements where A's are together (720) or using the gap method. - **A1**: Correct subtraction/calculation to find 1800.
题目 12 · Structured
9 分
In a triangle \( OPQ \), the position vectors of \( P \) and \( Q \) relative to \( O \) are \( \mathbf{p} \) and \( \mathbf{q} \) respectively. The point \( R \) lies on \( OP \) such that \( OR = \frac{2}{3}OP \). The point \( S \) lies on \( PQ \) such that \( PS = \frac{1}{4}PQ \). The lines \( OS \) and \( RQ \) intersect at the point \( T \).
(a) Express \( \overrightarrow{OS} \) in terms of \( \mathbf{p} \) and \( \mathbf{q} \).
(b) Given that \( \overrightarrow{OT} = \lambda \overrightarrow{OS} \) and \( \overrightarrow{RT} = \mu \overrightarrow{RQ} \), find the values of \( \lambda \) and \( \mu \).
Answer all questions. Show all necessary working clearly. Do not use a calculator where specified.
10 题目 · 62 分
题目 1 · short_answer
6 分
Find the exact value of \(\int_1^3 \left( \frac{e^{2x} - 2}{e^x} \right) \text{d}x\).
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解题
To find the exact value of the integral: \(\int_1^3 \left( \frac{e^{2x} - 2}{e^x} \right) \text{d}x\), first simplify the integrand: \(\frac{e^{2x} - 2}{e^x} = e^x - 2e^{-x}\). Now, integrate each term with respect to \(x\): \(\int (e^x - 2e^{-x}) \text{d}x = e^x + 2e^{-x}\). Apply the limits of integration from \(1\) to \(3\): \(\left[ e^x + 2e^{-x} \right]_1^3 = \left( e^3 + 2e^{-3} \right) - \left( e^1 + 2e^{-1} \right) = e^3 - e + \frac{2}{e^3} - \frac{2}{e}\).
评分标准
B1: Simplify the integrand to \(e^x - 2e^{-x}\); M1: Attempt to integrate, obtaining of the form \(e^x + k e^{-x}\); A1: Correct integrated expression \(e^x + 2e^{-x}\); M1: Substitute limits 3 and 1; A1: Correct substitution \((e^3 + 2/e^3) - (e + 2/e)\); A1: Exact final answer \(e^3 - e + 2/e^3 - 2/e\) or equivalent.
题目 2 · short_answer
6 分
An arithmetic progression has first term \(a\) and common difference \(d\). A geometric progression has first term \(a\) and common ratio \(r\). It is given that \(a = 4\) and \(r > 1\). The 3rd term of the arithmetic progression is equal to the 2nd term of the geometric progression. The 11th term of the arithmetic progression is equal to the 3rd term of the geometric progression. Find the value of \(d\) and the value of \(r\).
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解题
Let \(u_n = a + (n-1)d\) and \(v_n = a r^{n-1}\) with \(a = 4\). From \(u_3 = v_2\), we have \(4 + 2d = 4r \implies d = 2r - 2\) (Equation 1). From \(u_{11} = v_3\), we have \(4 + 10d = 4r^2 \implies 2 + 5d = 2r^2\) (Equation 2). Substituting Equation 1 into Equation 2: \(2 + 5(2r - 2) = 2r^2 \implies 2r^2 - 10r + 8 = 0 \implies r^2 - 5r + 4 = 0\). Factoring gives \((r - 4)(r - 1) = 0\). Since \(r > 1\), we have \(r = 4\). Substituting \(r = 4\) into Equation 1 gives \(d = 2(4) - 2 = 6\).
评分标准
B1: Form equation \(4 + 2d = 4r\) or equivalent; B1: Form equation \(4 + 10d = 4r^2\) or equivalent; M1: Eliminate \(d\) to form a quadratic equation in \(r\); A1: Solve quadratic to obtain \(r = 4\) (rejecting \(r = 1\)); M1: Substitute \(r\) to find \(d\); A1: Correct values \(d = 6, r = 4\).
题目 3 · short_answer
6 分
Solve the simultaneous equations: \(\log_3 x - 2\log_3 y = -1\) and \(2^{x+3} = 4^y\).
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解题
From the second equation, \(2^{x+3} = 2^{2y} \implies x + 3 = 2y \implies x = 2y - 3\) (Equation 1). From the first equation, \(\log_3\left(\frac{x}{y^2}\right) = -1 \implies \frac{x}{y^2} = \frac{1}{3} \implies y^2 = 3x\) (Equation 2). Substitute Equation 1 into Equation 2: \(y^2 = 3(2y - 3) \implies y^2 - 6y + 9 = 0 \implies (y - 3)^2 = 0 \implies y = 3\). Substituting \(y = 3\) into Equation 1 gives \(x = 2(3) - 3 = 3\).
评分标准
B1: Simplify the index equation to \(x + 3 = 2y\) or equivalent; M1: Apply log laws to combine LHS of the first equation; A1: Convert to exponential form to get \(y^2 = 3x\) or equivalent; M1: Substitute linear equation into quadratic to form a 3-term quadratic in one variable; A1: Solve quadratic to get \(y = 3\); A1: Correctly find \(x = 3\) and verify.
题目 4 · short_answer
7 分
Solve the equation \(\sqrt{3}\sin 2\theta + \cos 2\theta = 1\) for \(0 \le \theta \le \pi\), giving your answers in terms of \(\pi\).
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解题
Using the R-formula, let \(\sqrt{3}\sin 2\theta + \cos 2\theta = R\sin(2\theta + \alpha)\). Here, \(R = \sqrt{(\sqrt{3})^2 + 1^2} = 2\) and \(\tan\alpha = \frac{1}{\sqrt{3}} \implies \alpha = \frac{\pi}{6}\). The equation becomes \(2\sin(2\theta + \pi/6) = 1 \implies \sin(2\theta + \pi/6) = 1/2\). Since \(0 \le \theta \le \pi\), we have \(\pi/6 \le 2\theta + \pi/6 \le 13\pi/6\). In this interval, the solutions for \(2\theta + \pi/6\) are \(\pi/6\), \(5\pi/6\), and \(13\pi/6\). This gives \(2\theta = 0\), \(2\pi/3\), and \(2\pi\), which simplifies to \(\theta = 0\), \(\pi/3\), and \(\pi\).
评分标准
M1: Attempt R-formula or compound angle method; A1: Correctly identify \(R = 2\) and \(\alpha = \pi/6\) or equivalent; M1: Write equation as \(\sin(2\theta + \pi/6) = 1/2\); B1: Determine correct interval for transformed angle \([\pi/6, 13\pi/6]\); M1: Solve for transformed angle to find at least two correct values; A1: Correctly find any two of \(\theta = 0\), \(\pi/3\), \(\pi\); A1: Find all three correct solutions with no extra values in the range.
题目 5 · Structured
7 分
The functions \(f\) and \(g\) are defined as follows, for all real values of \(x\):
\(f(x) = 2x^2 + 3\)
\(g(x) = e^{2x} - 3\)
(a) Find \(fg(0)\).
(b) Find \(gg(x)\).
(c) Solve the equation \(g^{-1}(x) = \frac{1}{2}\ln 4\).
**(c)** - **M1**: Rearranging \(y = e^{2x}-3\) to make \(x\) the subject (condone one error) - **A1**: Finding \(g^{-1}(x) = \frac{1}{2}\ln(x+3)\) oe - **A1**: For \(x = 1\)
题目 6 · Structured
4 分
Find the range of values of \(p\) for which the curve \(y = x^2 - px + (2p + 5)\) lies completely above the \(x\)-axis.
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解题
For the quadratic curve to lie completely above the \(x\)-axis, we require the coefficient of \(x^2\) to be positive (which is \(1 > 0\)) and the discriminant to be negative (\(b^2 - 4ac < 0\)).
Convert back to \(x\) and \(y\): \(\log_5 x = 2 \implies x = 5^2 = 25\). \(\log_5 y = 1 \implies y = 5^1 = 5\).
Therefore, the solution is \(x = 25\) and \(y = 5\).
评分标准
- **M1**: For a valid attempt to eliminate one variable (either \(\log_5 x\) or \(\log_5 y\)) - **A1**: For finding \(\log_5 x = 2\) or \(\log_5 y = 1\) - **A1**: For finding the other logarithmic value correctly - **A1**: For \(x = 25\) (dep on first M1) - **A1**: For \(y = 5\) (dep on first M1)
题目 8 · Structured
6 分
Find the exact value of \(\int_{1}^{4} \frac{(2x - 3)^2}{x^2} \, dx\).
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解题
First, expand the numerator of the integrand: \((2x - 3)^2 = 4x^2 - 12x + 9\).
Now rewrite the integrand by dividing each term by \(x^2\): \(\frac{4x^2 - 12x + 9}{x^2} = 4 - \frac{12}{x} + 9x^{-2}\).
Integrate each term with respect to \(x\): \(\int \left(4 - \frac{12}{x} + 9x^{-2}\right) dx = 4x - 12\ln|x| - 9x^{-1} + C = 4x - 12\ln|x| - \frac{9}{x} + C\).
Substitute the limits from 1 to 4: At \(x = 4\): \(4(4) - 12\ln 4 - \frac{9}{4} = 16 - 12\ln(2^2) - \frac{9}{4} = 16 - 24\ln 2 - 2.25 = 13.75 - 24\ln 2\).
Subtract the value at the lower limit from the value at the upper limit: \((13.75 - 24\ln 2) - (-5) = 18.75 - 24\ln 2\).
Convert 18.75 to an exact fraction: \(18.75 = \frac{75}{4}\).
So the exact value is \(\frac{75}{4} - 24\ln 2\).
评分标准
- **B1**: Correctly expands \((2x-3)^2 = 4x^2 - 12x + 9\) - **M1**: For dividing each term by \(x^2\) to get separate powers of \(x\) - **B2**: For correct integration of at least two terms (B1 for one correct term) - Integration is: \(4x - 12\ln x - \frac{9}{x}\) - **M1**: For substituting limits of 1 and 4 into their integrated expression - **A1**: For \(\frac{75}{4} - 24\ln 2\) or exact equivalent (e.g. \(18.75 - 12\ln 4\))
题目 9 · Structured
9 分
A particle travels in a straight line. Its displacement, \(s\) metres, from the origin at time \(t\) seconds, where \(t \ge 0\), is given by \(s = \ln(t^2 + 5) - \frac{1}{3}t\).
(a) Find expressions for the velocity, \(v\text{ ms}^{-1}\), and acceleration, \(a\text{ ms}^{-2}\), of the particle.
(b) Find the times when the particle is at rest.
(c) Find the acceleration at each of these times.
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解题
**(a)** Velocity is the first derivative of displacement with respect to time: \(v = \frac{ds}{dt} = \frac{d}{dt}\left( \ln(t^2 + 5) - \frac{1}{3}t \right) = \frac{2t}{t^2 + 5} - \frac{1}{3}\).
Acceleration is the derivative of velocity with respect to time: \(a = \frac{dv}{dt} = \frac{d}{dt}\left( \frac{2t}{t^2 + 5} - \frac{1}{3} \right)\). Using the quotient rule: \(a = \frac{2(t^2 + 5) - 2t(2t)}{(t^2 + 5)^2} = \frac{2t^2 + 10 - 4t^2}{(t^2 + 5)^2} = \frac{10 - 2t^2}{(t^2 + 5)^2}\).
**(b)** The particle is at rest when \(v = 0\): \(\frac{2t}{t^2 + 5} - \frac{1}{3} = 0\) \(\frac{2t}{t^2 + 5} = \frac{1}{3}\) \(6t = t^2 + 5\) \(t^2 - 6t + 5 = 0\) \((t - 1)(t - 5) = 0\). So, \(t = 1\) and \(t = 5\).
**(c)** Substitute \(t = 1\) and \(t = 5\) into the expression for acceleration: At \(t = 1\): \(a = \frac{10 - 2(1)^2}{(1^2 + 5)^2} = \frac{8}{36} = \frac{2}{9}\text{ ms}^{-2}\).
**(a)** - **B1**: For velocity \(v = \frac{2t}{t^2 + 5} - \frac{1}{3}\) - **M1**: Correct use of quotient rule or product rule on their velocity - **A1**: For \(\frac{2(t^2 + 5) - 4t^2}{(t^2 + 5)^2}\) oe - **A1**: Simplifies to \(a = \frac{10 - 2t^2}{(t^2 + 5)^2}\)
**(b)** - **B1**: Sets \(v = 0\) - **M1**: Forms a 3-term quadratic in \(t\) and attempts to solve: \(t^2 - 6t + 5 = 0\) - **A1**: For \(t = 1\) and \(t = 5\) (no other values)
**(c)** - **M1**: Substitutes their positive values of \(t\) into their acceleration expression - **A1**: Both \(\frac{2}{9}\) and \(-\frac{2}{45}\) (accept decimal equivalents correct to 3sf: 0.222 and -0.0444)
题目 10 · Structured
6 分
An arithmetic progression (AP) and a geometric progression (GP) have the following properties:
- The 1st terms of the AP and GP are both 4. - The 3rd term of the AP is equal to the 2nd term of the GP. - The 11th term of the AP is equal to the 3rd term of the GP. - The common ratio of the GP is greater than 1.
Find the common difference of the AP and the common ratio of the GP.
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解题
Let the first term be \(a = 4\). Let \(d\) be the common difference of the AP. Let \(r\) be the common ratio of the GP.
From the given properties: 1) The 3rd term of the AP is \(a + 2d = 4 + 2d\). The 2nd term of the GP is \(ar = 4r\). Since they are equal: \(4 + 2d = 4r \implies 2 + d = 2r \implies d = 2r - 2\).
2) The 11th term of the AP is \(a + 10d = 4 + 10d\). The 3rd term of the GP is \(ar^2 = 4r^2\). Since they are equal: \(4 + 10d = 4r^2\).
Substitute the expression for \(d\) into this second equation: \(4 + 10(2r - 2) = 4r^2\) \(4 + 20r - 20 = 4r^2\) \(4r^2 - 20r + 16 = 0\).
Divide the entire equation by 4: \(r^2 - 5r + 4 = 0\) \((r - 1)(r - 4) = 0\).
This gives two possible values for \(r\): \(r = 1\) or \(r = 4\).
Since the common ratio of the GP is greater than 1, we must have \(r = 4\).
Now substitute \(r = 4\) back to find \(d\): \(d = 2(4) - 2 = 6\).
So, the common difference of the AP is 6 and the common ratio of the GP is 4.
评分标准
- **B1**: For \(4 + 2d = 4r\) oe - **B1**: For \(4 + 10d = 4r^2\) oe - **M1**: For attempting to eliminate one variable to form a quadratic equation (usually in \(r\)) - **A1**: For forming a correct quadratic: \(4r^2 - 20r + 16 = 0\) (or simplified \(r^2 - 5r + 4 = 0\)) or \(2d^2 - 12d = 0\) - **A1**: For finding the correct value \(r = 4\) (rejecting \(r = 1\) with reason or implicitly) - **A1**: For finding the correct value \(d = 6\)
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