Cambridge KS3 Maths: Solving Linear Equations (p141 Q2) | 剑桥 KS3 数学：解一元一次方程（第141页第2题）

📚 Cambridge KS3 Maths: Solving Linear Equations (p141 Q2) | 剑桥 KS3 数学：解一元一次方程（第141页第2题）

Welcome to this Cambridge KS3 Maths revision guide. We will work through a key algebra topic: solving linear equations in one variable. This includes one-step and two-step equations, equations with brackets, equations with fractions, and equations with unknowns on both sides. The methods shown here are directly relevant to Cambridge Checkpoint questions, including the exercise found on page 141 question 2.

欢迎阅读本篇剑桥 KS3 数学复习指南。我们将系统学习一个核心代数主题：解一元一次方程。内容包括一步和两步方程、含括号的方程、含分数的方程以及未知数在等式两边的方程。这里展示的方法与 Cambridge Checkpoint 试题直接相关，包括第141页第2题的练习。

1. What Is a Linear Equation? | 什么是一元一次方程？

A linear equation is an algebraic statement that says two expressions are equal, and the unknown variable appears only to the first power. For example, 3x + 5 = 20 and 4(x – 2) = 16 are linear equations. The word ‘linear’ comes from the fact that if you drew y = 3x + 5, you would get a straight line.

一元一次方程是一个代数等式，表示两个表达式相等，而且未知数只以一次方的形式出现。例如 3x + 5 = 20 和 4(x – 2) = 16 都是一元一次方程。单词 ‘linear’ 源于这样一个事实：如果画出 y = 3x + 5 的图像，你会得到一条直线。

3x + 5 = 20

x = 5

In this example, x = 5 is the solution because substituting 5 gives 3 × 5 + 5 = 20, which is true. Linear equations can have one solution, no solution, or infinitely many solutions, but at KS3 we mostly meet equations with exactly one solution.

在这个例子中，x = 5 是解，因为代入 5 得到 3 × 5 + 5 = 20，等式成立。线性方程可能有一个解、

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