Collecting Like Terms | 合并同类项

📚 Collecting Like Terms | 合并同类项

In IGCSE algebra, many questions ask you to simplify an expression such as 6x + 3y – 2x + 5y. Collecting like terms is the first essential skill: it lets you replace a long expression with a shorter equivalent one. This guide explains what like terms are, how to combine them correctly, and how to avoid common exam errors.

在 IGCSE 代数中，许多题目要求你化简如 6x + 3y – 2x + 5y 这样的表达式。合并同类项是第一项核心技能：它能把一个较长的表达式写成等价的简短形式。本文说明什么是同类项、如何正确合并以及如何避免常见考试错误。

1. What Are Like Terms? | 什么是同类项

A term is a single number, letter, or product of numbers and letters, such as 4x, -3y, 7x², or 9. Like terms have exactly the same variable part and the same powers. The coefficient, which is the number in front, can be different.

项是单个数字、字母或数字与字母的乘积，例如 4x、-3y、7x² 或 9。同类项具有完全相同的字母部分和相同的指数。系数，也就是字母前面的数字，可以不同。

For example, 5x and -3x are like terms because both have x to the power 1. However, 4x and 4x² are not like terms, because x and x² are different powers. Also, 2xy and -7xy are like terms, while 5 and -9 are like constant terms.

例如，5x 和 -3x 是同类项，因为两者都含有 x 的一次方。然而，4x 与 4x² 不是同类项，因为 x 和 x² 是不同的幂。另外，2xy 与 -7xy 是同类项，而 5 和 -9 是同类常数项。

2. Why ‘Combining’ Matters in IGCSE | 为什么在 IGCSE 中合并很重要

Many IGCSE questions do not only ask you to simplify an expression; they also expect simplified answers in algebra, equation solving, and function work. If you do not collect like terms, your final answer may be mathematically equivalent but not in the required simplified form, so marks can be lost.

许多 IGCSE 题目不仅要求你化简表达式，在代数、解方程和函数等内容中也要求答案必须化简。如果不合并同类项，最终答案可能在数学上等价，但不是题目要求的化简形式，因此可能

Published by TutorHao | IGCSE Mathematics Revision Series | aleveler.com

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