Simulated Unit Test Analysis: CCEA A-Level Further Mathematics | 模拟单元测试解析：CCEA 进阶数学

📚 Simulated Unit Test Analysis: CCEA A-Level Further Mathematics | 模拟单元测试解析：CCEA 进阶数学

This article provides a detailed walkthrough of a simulated unit test for CCEA Further Mathematics. Each section tackles a core topic, presents a typical exam‑style question, and explains the solution step by step. By working through these model answers, you will sharpen your problem‑solving techniques and deepen your understanding of the Further Pure syllabus.

本文深入解析一份为 CCEA 进阶数学设计的模拟单元测试。每个小节聚焦一个核心主题，先给出一道典型考题，再逐步拆解详细解答过程。通过研习这些范例解答，你将优化解题思路，巩固进阶纯数课程的关键知识。

1. Complex Numbers: Modulus, Argument and Equations | 复数：模、辐角与方程求解

Question: Let z = 3 - 4i. Find |z| z⁻¹ in the form a + bi. Hence solve the equation w² = 3 - 4i, giving both roots in modulus‑argument form.

题目：设 z = 3 - 4i。求 |z|、arg z（弧度制，保留三位有效数字）以及 z⁻¹。将 z⁻¹ 表为 a + bi 的形式。据此解方程 w² = 3 - 4i，并将两个根用模‑辐角形式表示。

We first compute the modulus: |z| = √(3² + (-4)²) = √9+16 = √25 tan(4/3) + 2π, or equivalently -0.927 rad (to 3 s.f.). We can also quote arg z = 5.36 rad.

先计算模：|z| = √(3² + (-4)²) = √9+16 = √25 = 5。辐角为 arg z = arctan(-4/3)，位于第四象限，故 arg z = -0.927 弧度（保留三位有效数字），也可取主值 5.36 弧度。

ominator by the conjugate 3 + 4i to obtain z⁻¹ = (3+4i)/(9+16) = (3+4i)/25 = 0.12 + 0.16i.

倒数为 z⁻¹ = 1/(3 - 4i)。分子分母同乘共轭 3+4i，得 z⁻¹ = (3+4i)/(9+16) = (3+4i)/25 = 0.12 + 0.16i。

To solve w² = 3 - 4i, write the right‑d side in polar form: 5(cos θ + i sin θ) with θ = -0.927 rad. The two square roots are w = √5 [cos(θ/2 + kπ) + i sin(θ/2 + kπ)] for k = 0, 1. Since √5 ≈ 2.236, the roots are 2.24(cos(-0.464) + i sin(-0.464)) and 2.24(cos 2.68 + i sin 2.68).

为解 w² = 3 - 4i，先将右端化为极坐标：5(cos θ + i sin θ)，其中 θ = -0.927 弧度。两个平方根为 w = √5 [cos(θ/2 + kπ) + i sin(θ/2 + kπ)]，k = 0, 1。√5 ≈ 2.236，两根分别为 2.24(cos(-0.464) + i sin(-0.464)) 与 2.24(cos 2.68 + i sin 2.68)。

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2. Matrices: Inverse and Transformation | 矩阵：逆矩阵与变换

. Determine A⁻¹ and verify that AA⁻¹ = I. The transformation T maps a point (x, y) onto (x', y') where [x'; y' the image of the point (1, 1) under T, and give the point whose image under T is (5, 11).

题目：A = [1 2; 3 4]。求 A⁻¹ 并验证 AA⁻¹ = I。变换 T 将点 (x, y) 映射为 (x', y')，满足 [x'; y'] = A [x; y]。求点 (1, 1) 在 T 下的像，并求出在 T 下像为 (5, 11) 的原像点。

]. Multiply A A⁻¹ to confirm: [1 2; 3 4] × [-2 1; 1.5 -0.5] = [ -2+3 1-1 ; -6+6 3-2 ] = I.

对于 2×2 矩阵 [a b; c d]，逆矩阵为 (1/(ad-bc)) [d -b; -c a]。此处 det A = 1×4 - 2×3 = -2。因此 A⁻¹ = (1/-2)[4 -2; -3 1] = [-2 1; 1.5 -0.5]。验算 AA⁻¹：第一行 (-2+3, 1-1) = (1,0)；第二行 (-6+6, 3-2) = (0,1)，即单位阵。

The image of (1,1) under T is A (1,1)ᵀ = [1+2; 3+4] = (3, 7). To find the pre‑ ; 11], i.e. [x; y] = A⁻¹ [5; 11] = [-2 1; 1.5 -0.5][5; 11] = [ -10+11; 7.5-5.5 ] = (1, 2).

(1,1) 在 T 下的像为 A (1,1)ᵀ = [1+2; 3+4] = (3, 7)。欲求像为 (5,11) 的原像，解 A [x; y] = [5; 11]，即 [x; y] = A⁻¹ [5; 11] = [-2 1; 1.5 -0.5][5; 11] = [ -10+11; 7.5-5.5 ] = (1, 2)。

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3. Further Calculus: Integration by Parts | 进阶微积分：分部积分

Question: Evaluate ∫ x sin x dx using integration by parts. Hence evaluate ∫ x² cos x dx.

题目：用分部积分法求 ∫ x sin x dx，并据此求 ∫ x² cos x dx。

u/dx = 1, v = -cos x. Then ∫ x sin x dx = -x cos x - ∫ (-cos x) dx = -x cos x + sin x + C.

设 u = x，dv/dx = sin x，则 du/dx = 1，v = -cos x。于是 ∫ x sin x dx = -x cos x - ∫ (-cos x) dx = -x cos x + sin x + C。

x sin x dx = x² sin x - 2 ∫ x sin x dx. Substitute the known integral: = x² sin x - 2( -x cos x + sin x ) + C = x² sin x + 2x cos x - 2 sin x + C.

对于 ∫ x² cos x dx，再次分部积分：令 u = x²，dv/dx = cos x，得 du/dx = 2x，v = sin x。积分化为 x² sin x - ∫ 2x sin x dx = x² sin x - 2 ∫ x sin x dx。代入已知积分：= x² sin x - 2( -x cos x + sin x ) + C = x² sin x + 2x cos x - 2 sin x + C。

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4. Hyperbolic Functions: Solving Equations | 双曲函数：方程求解

Solve the equation 5 cosh x - 4 sinh x = 5, giving your answers in exact logarithmic form.

题目：解方程 5 cosh x - 4 sinh x = 5，答案用精确的对数形式给出。

Express cosh x and sinh x in terms of exponentials: cosh x = (eˣ + e⁻ˣ)/2, sinh x = (eˣ - e⁻ˣ)/2. Substituting: 5(eˣ + e⁻ˣ)/2 - 4(eˣ - e⁻ˣ)/2 = 5. Multiply by 2: 5eˣ + 5e⁻ˣ - 4eˣ + 4e⁻ˣ = 10 → eˣ + 9e⁻ˣ = 10.

用指数形式表示双曲函数：cosh x = (eˣ + e⁻ˣ)/2，sinh x = (eˣ - e⁻ˣ)/2。代入得 5(eˣ + e⁻ˣ)/2 - 4(eˣ - e⁻ˣ)/2 = 5。两边乘 2：5eˣ + 5e⁻ˣ - 4eˣ + 4e⁻ˣ = 10 → eˣ + 9e⁻ˣ = 10。

Multiply through by eˣ to obtain a quadratic in eˣ: (eˣ)² - 10 eˣ + 9 = 0 → (eˣ - 1)(eˣ - 9) = 0. Hence eˣ = 1 or eˣ = 9. Taking natural logs gives x = ln 1 = 0 or x = ln 9 = 2 ln 3.

两边乘 eˣ 得到关于 eˣ 的二次方程：(eˣ)² - 10 eˣ + 9 = 0 → (eˣ - 1)(eˣ - 9) = 0。故 eˣ = 1 或 eˣ = 9。取自然对数得 x = ln 1 = 0 或 x = ln 9 = 2 ln 3。

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5. First Order Differential Equations: Integrating Factor | 一阶微分方程：积分因子

differential equation dy/dx + y tan x = sec x, subject to the initial condition y(0) = 1.

题目：解微分方程 dy/dx + y tan x = sec x，并满足初始条件 y(0) = 1。

The equation is linear with integrating factor μ(x) = e^{∫ tan x dx} = e^{ln sec x} x + y sec x tan x = sec² x. The left side is d/dx (y sec x). Thus d/dx (y sec x) = sec² x.

方程为线性，积分因子 μ(x) = e^{∫ tan x dx} = e^{ln sec x} = sec x。以 sec x 乘方程：sec x dy/dx + y sec x tan x = sec² x。左边恰为 d/dx (y sec x)，故 d/dx (y sec x) = sec² x。

. Apply y(0)=1: 1 = sin 0 + C cos 0 → C = 1. The particular solution is y = sin x + cos x.

两边积分：y sec x = ∫ sec² x dx = tan x + C。因此 y = (tan x + C) cos x = sin x + C cos x。代入 y(0)=1：1 = sin 0 + C cos 0 → C = 1。特解为 y = sin x + cos x。

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6. Second Order Differential Equations: Non‑homogeneous | 二阶微分方程：非齐次

Question: Find the general solution of the differential equation d²y/dx² - 4y = 2e²ˣ.

题目：求微分方程 d²y/dx² - 4y = 2e²ˣ 的通解。

First solve the homogeneous equation: auxiliary equation m² - 4 = 0 ⇒ m = ±2. So the complementary function is y_c = A e²ˣ + B e⁻²ˣ.

先解齐次方程：辅助方程 m² - 4 = 0 ⇒ m = ±2，故余函数为 y_c = A e²ˣ + B e⁻²ˣ。

The right‑hand side 2e²ˣ suggests a particular integral of the form C x e²ˣ, since e²ˣ is already part of the complementary function. Let y_p = C x e²ˣ. Then y_p' = C e²ˣ + 2C x e²ˣ, y_p'' = 4C e²ˣ + 4C x e²ˣ. Substitute into the LHS: (4C e²ˣ + 4C x e²ˣ) - 4(C x e²ˣ) = 4C e²ˣ. Set this equal to 2e²ˣ ⇒ 4C = 2 ⇒ C = 1/2. Thus y_p = (1/2) x e²ˣ.

右端 2e²ˣ 提示特解形式为 C x e²ˣ，因 e²ˣ 已在余函数中。设 y_p = C x e²ˣ，则 y_p' = C e²ˣ + 2C x e²ˣ，y_p'' = 4C e²ˣ + 4C x e²ˣ。代入左边：(4C e²ˣ + 4C x e²ˣ) - 4(C x e²ˣ) = 4C e²ˣ。令其等于 2e²ˣ，得 4C = 2 ⇒ C = 1/2。于是特解为 y_p = (1/2) x e²ˣ。

The general solution is y = y_c + y_p = A e²ˣ + B e⁻²ˣ + (1/2) x e²ˣ.

通解为 y = A e²ˣ + B e⁻²ˣ + (1/2) x e²ˣ。

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7. Polar Coordinates: Area and Sketching | 极坐标：作图与面积

tch the curve r = 2 + 2 sin θ, 0 ≤ θ ≤ 2π. Calculate the total area enclosed by the curve.

题目：绘制曲线 r = 2 + 2 sin θ，0 ≤ θ ≤ 2π 的图像，并计算曲线所围成的总面积。

about the vertical axis. It passes through the pole when r = 0, i.e. when 2 + 2 sin θ = 0 ⇒ sin θ = -1 ⇒ θ = 3π/2. The maximum r is 4 at θ = π/2.

该曲线为一条心形线，关于竖直轴对称。当 r = 0 时经过极点，即 2 + 2 sin θ = 0 ⇒ sin θ = -1 ⇒ θ = 3π/2。最大 r 值为 4，出现在 θ = π/2。

(1 + 2 sin θ + sin² θ) dθ = 2 ∫₀²π (1 + 2 sin θ + sin² θ) dθ. Use sin² θ = (1 - cos 2θ)/2.

极坐标曲线所围面积公式为 (1/2) ∫₀²π r² dθ。此处 r² = 4(1 + sin θ)² = 4(1 + 2 sin θ + sin² θ)。故面积 = (1/2) ∫₀²π 4(1 + 2 sin θ + sin² θ) dθ = 2 ∫₀²π (1 + 2 sin θ + sin² θ) dθ。利用 sin² θ = (1 - cos 2θ)/2。

) ∫₀²π (1 - cos 2θ) dθ = (1/2)[θ - (1/2) sin 2θ]₀²π = π. So the area = 2(2π + 0 + π) = 6π.

逐项积分：∫₀²π 1 dθ = 2π，∫₀²π 2 sin θ dθ = 0，∫₀²π sin² θ dθ = (1/2) ∫₀²π (1 - cos 2θ) dθ = (1/2)[θ - (1/2) sin 2θ]₀²π = π。因此面积 = 2(2π + 0 + π) = 6π。

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8. Series: Maclaurin Expansion and Limits | 级数：麦克劳林展开与极限

Question: Obtain the Maclaurin series for sin x up to the term in x⁵. Hence, or otherwise, evaluate lim_x→0 (sin x - x) / x³.

题目：求 sin x 的麦克劳林级数，展开至 x⁵ 项。据此或用其他方法求极限 lim_x→0 (sin x - x) / x³。

The Maclaurin series is f(x) = f(0) + f'(0)x + f''(0)x²/2! + f'''(0)x³/3! + ... For sin x: f(0)=0, f'(x)=cos x → f'(0)=1, f''(x)=-sin x → f''(0)=0, f'''(x)=-cos x → f'''=-1, f⁽⁴⁾(x)=sin x → f⁽⁴⁾(0)=0, f⁽⁵⁾(x)=cos x → f⁽⁵⁾(0)=1. Thus sin x ≈ x - x³/6 + x⁵/120.

麦克劳林公式为 f(x) = f(0) + f'(0)x + f''(0)x²/2! + ... 对 sin x：f(0)=0，f'(x)=cos x → f'(0)=1，f''(x)=-sin x → f''(0)=0，f'''(x)=-cos x → f'''(0)=-1，f⁽⁴⁾(x)=sin x → f⁽⁴⁾(0)=0，f⁽⁵⁾(x)=cos x → f⁽⁵⁾(0)=1。故 sin x ≈ x - x³/6 + x⁵/120。

/ x³ = ( - x³/6 + higher terms ) / x³ = -1/6 + terms in x. As x→0, the limit equals -1/6.

现考察极限：(sin x - x)/x³ = ( (x - x³/6 + x⁵/120 - ...) - x ) / x³ = ( - x³/6 + 更高次项 ) / x³ = -1/6 + 含 x 项。当 x→0 时，极限为 -1/6。

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9. Vectors: Intersection of Two Planes | 向量：两平面的交线

Π₂: 2x - y + z = 3. Find a vector equation of the line of intersection of the two planes.

题目：已知两平面 Π₁: x + y + z = 6，Π₂: 2x - y + z = 3。求这两平面交线的向量方程。

- 1·1, 1·(-1) - 1·2) = (1+1, 2-1, -1-2) = (2, 1, -3). So direction vector d = 2i + j - 3k.

直线的方向向量平行于两平面法向量的叉积 n₁ = (1,1,1) 与 n₂ = (2,-1,1)。计算 n₁ × n₂ = (1·1 - 1·(-1), 1·2 - 1·1, 1·(-1) - 1·2) = (2, 1, -3)。故方向向量 d = 2i + j - 3k。

So a point on the line is (3, 3, 0). The vector equation is r = (3, 3, 0) + λ (2, 1, -3).

为找直线上一点，可设 z = 0，解方程组 x + y = 6, 2x - y = 3。两式相加得 3x = 9 → x = 3，则 y = 3。故直线上一点为 (3, 3, 0)。向量方程为 r = (3, 3, 0) + λ (2, 1, -3)。

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10. Proof by Induction: Sum of Squares | 归纳法证明：平方和

Question: Prove by mathematical induction that for all positive integers n, Σ_r=1ⁿ r² = n(n+1)(2n+1)/6.

题目：用数学归纳法证明，对所有正整数 n，有 Σ_r=1ⁿ r² = n(n

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