📚 Edexcel Further Maths Core Pure 2: Key Topics and Exam Strategies | Edexcel 进阶数学 Core Pure 2:核心考点与备考策略
Edexcel Further Maths Core Pure 2 extends Core Pure 1 with deeper complex numbers, polar coordinates, hyperbolic functions, series and differential equations. This revision guide summarises the key techniques and common exam pitfalls.
Edexcel 进阶数学 Core Pure 2 在 Core Pure 1 的基础上深入拓展复数、极坐标、双曲函数、级数和微分方程等内容。本复习指南总结关键技巧与常见考试陷阱。
1. Complex Numbers and de Moivre's Theorem | 复数与棣莫弗定理
are expressed in modulus-argument form z = r(cos θ + i sin θ) and exponential form z = reiθ. De Moivre' + i sin θ)ⁿ = cos nθ + i sin nθ. This gives a fast way to raise complex numbers to powers.
在 Core Pure 2 中,复数用模-辐角形式 z = r(cos θ + i sin θ) 和指数形式 z = reiθ 表示。棣莫弗定理指出,对任何整数 n 有 (cos θ + i sin θ)ⁿ = cos nθ + i sin nθ。它提供了快速计算复数幂的方法。
zⁿ = rⁿ(cos nθ + i sin nθ) = rⁿ einθ
You must also use de Moivre' h as cos 3θ = 4 cos³ θ − 3 cos θ, by expanding (cos θ + i sin θ)³ and equating real parts.
你还必须会用棣莫弗定理推导倍角恒等式,例如 cos 3θ = 4 cos³ θ − 3 cos θ,方法是展开 (cos θ + i sin θ)³ 并比较实部。
ke is taking the wrong quadrant for θ = arg z. Always sketch the Argand diagram: z = 1 + i√3 has r = 2 and θ = π/3, so z⁶ = 64(cos 2π + i sin 2π) = 64.
常见错误包括对 θ = arg z 取错象限。一定要画 Argand 图:例如 z = 1 + i√3 有 r = 2 且 θ = π/3,所以 z⁶ = 64(cos 2π + i sin 2π) = 64。
2. Roots of Unity and Complex Roots | 单位根与复数根
form and take the nth root. The n distinct roots are evenly spaced around a circle of radius r1/n, separated by angle 2π/n.
要求解 zⁿ = w,先把 w 写成指数形式并开 n 次方。n 个不同根均匀分布在半径为 r1/n 的圆上,相邻根的角度差为 2π/n。
zₖ = r1/n [ cos((θ + 2kπ)/n) + i sin((θ + 2kπ)/n) ], k = 0, 1, ..., n−1
Roots of unity occur when w = 1. For example, the cube roots of unity are 1, ω = −½ + (√3/2)i and ω² = −½ − (√3/2)i, and they satisfy 1 + ω + ω² = 0.
当 w = 1 时得到的根称为单位根。例如三次单位根为 1、ω = −½ + (√3/2)i 和 ω² = −½ − (√3/2)i,并且满足 1 + ω + ω² = 0。
Exam questions often ask for the sum or product of roots, or for a polynomial with given complex roots. Use the symmetry of the circle to simplify the calculation.
考题经常要求根的和或积,或写出具有给定复数根的多项式。利用圆的对称性可以简化计算。
3. Loci in the Complex Plane | 复平面上的轨迹
Loci problems ask you to describe or sketch sets of points satisfying conditions such as |z − a| = r, |z − a| = |z − b|, or arg(z − a) = θ.
轨迹问题要求描述或画出满足条件的点集,例如 |z − a| = r、|z − a| = |z − b| 或 arg(z − a) = θ。
The equation |z − a| = r is a circle centre a and radius r; |z − a| = |z − b| is the perpendicular bisector of the segment joining a and b; arg(z − a) =
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