📚 IGCSE WJEC Maths: Last-Minute Revision Notes | IGCSE WJEC 数学：考前冲刺笔记
This article provides essential last-minute revision notes for IGCSE WJEC Mathematics, covering the most important formulas, concepts and exam tips across all topics. Use it to refresh your memory, avoid common pitfalls, and boost your confidence before the exam.
本文提供 IGCSE WJEC 数学考前精华复习笔记，涵盖所有主题最重要的公式、概念和应试技巧。用它快速回顾知识、避开常见陷阱，在考前增强信心。
1. Number | 数
h bound to use for a given calculation (e.g., maximum area needs upper bounds of lengths).
测量值四舍五入到某单位时，真值在 ±0.5 单位内。上界 = 值 + 0.5×单位，下界 = 值 − 0.5×单位。计算时务必根据问题选择使用哪个界（如求最大面积需用长度的上界）。
ly by a power of 10 equal to the number of repeating digits and subtract. For example, 0.3̅7: let x = 0.3737…, 100x = 37.3737…, 99x = 37, so x = 37/99.
循环小数化分数：乘以 10 的幂（幂次等于循环节位数）后相减。如 0.3̅7，令 x = 0.3737…，100x = 37.3737…，99x = 37，x = 37/99。
Percentage change = (difference / original) × 100%. For repeated changes, use multipliers: a 15% increase gives multiplier 1.15; a 20% es 0.80. Compound percentage problems can be solved by multiplying successive multipliers.
百分比变化 = (差值/原值) × 100%。多次变化用乘数解决：增加15%乘1.15；减少20%乘0.80。复利类问题即连续乘以乘数。
ivide numbers and subtract exponents. Ensure the final answer is in correct standard form.
标准形式：a × 10ⁿ (1 ≤ a < 10)。乘法：数字相乘，指数相加：(A×10ᵐ)×(B×10ⁿ) = (A×B) × 10ᵐ⁺ⁿ。除法：数字相除，指数相减。最终答案必须化为正确的标准形式。
highest powers of all primes present. HCF = product of the lowest powers of common primes.
质因数分解：用因子树将数字写成质数乘积。LCM = 所有质数的最高次幂乘积；HCF = 公共质数的最低次幂乘积。
Simplify surds: √a×b = √a × √b. Always look for square factors. Rationalise the denominator by multiplying top and bottom by the conjugate if necessary: 1/(√a − √b) becomes (√a + √b)/(a − b).
简化根式：√a×b = √a × √b，始终寻找平方因子。分母有理化时，可乘以共轭式：1/(√a − √b) = (√a + √b)/(a − b)。
2. Algebra | 代数
Solving linear equations: perform the same operation (add, subtract, multiply, divide) on both sides to isolate the unknown. Always substitute your answer back to check. Brackets should be expanded first.
解线性方程：在等号两边执行相同运算以分离未知数。先展开括号，再将解代入原方程检验。
x² + bx + c with a ≠ 1, use decomposition: find two numbers that multiply to ac and add to b, then factor by grouping.
因式分解二次式：x² + bx + c = (x + p)(x + q)，其中 p+q
Published by TutorHao | IGCSE Mathematics Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图