📚 Solving Linear Equations: Balanced Methods for KS3 | 解一元一次方程:KS3 平衡法与技巧
Linear equations are one of the most important building blocks of KS3 Cambridge mathematics. They appear in algebra, number problems, geometry and real-life contexts, so being able to solve them confidently is essential for progress.
一元一次方程是 KS3 剑桥数学最重要的基础模块之一。它们出现在代数、数论问题、几何和实际情境中,因此能够熟练解方程对于后续学习至关重要。
1. What Is a Linear Equation? | 什么是一元一次方程?
ower 1. For example, 2x + 3 = 11 is a linear equation because the highest power of x is 1.
一元一次方程是将两个代数式用等号连接起来的等式,其中未知数字母通常为 x,并且 x 的最高次数为 1。例如 2x + 3 = 11 是一元一次方程,因为 x 的最高次数是 1。
ve an equals sign, while an equation such as 3x + 5 = 20 states that two things are equal.
方程与表达式不同。像 3x + 5 这样的表达式没有等号,而像 3x + 5 = 20 这样的方程则说明两个量相等。
The solution of a linear equation is the value of x that makes the equation true. Solving means finding that value systematically rather than guessing.
一元一次方程的解就是使等式成立的 x 的值。解方程是指用系统的方法求出这个值,而不是靠猜测。
2x + 3 = 11 ⇒ x = 4
2. The Balance Method | 平衡法
Think of an equation as a balanced set of scales. The left-hand side and the right-hand side must always stay equal, so whatever you do to one side, you must do to the other side.
把方程想象成一台平衡的天平。左边和右边必须始终保持相等,所以对一边做什么运算,对另一边也要做相同的运算。
If you add the same number to both sides, subtract the same number, multiply both sides by the same non-zero number, or divide both sides by the same non-zero number, the equality is preserved.
如果两边同时加上同一个数、同时减去同一个数、同时乘以同一个非零数或同时除以同一个非零数,等式仍然成立。
int level. It helps you keep the equation true while you rearrange it into the form x = a.
平衡法是 KS3 和剑桥 Checkpoint 阶段解所有方程的基础。它能帮助你在逐步变形为 x = a 的形式时保持等式始终成立。
3. Solving One-Step Equations | 解一步方程
on to isolate x. For x + 5 = 12, subtract 5 from both sides: x + 5 - 5 = 12 - 5, so x = 7.
有些方程只需要一步运算就能求出 x。对于 x + 5 = 12,两边同时减去 5:x + 5 - 5 = 12 - 5,所以 x = 7。
For x - 7 = 3, add 7 to both sides: x - 7 + 7 = 3 + 7, giving x = 10.
对于 x - 7 = 3,两边同时加上 7:x - 7 + 7 = 3 + 7,得到 x = 10。
For 3x = 18, divide both sides by 3: 3x ÷ 3 = 18 ÷ 3, so x = 6.
对于 3x = 18,两边同时除以 3:3x ÷ 3 = 18 ÷ 3,所以 x = 6。
For x ÷ 4 = 9, multiply both sides by 4: x ÷ 4 × 4 = 9 × 4, so x = 36.
对于 x ÷ 4 = 9,两边同时乘以 4:x ÷ 4 × 4 = 9 × 4,所以 x = 36。
A quick table can help you remember the inverse operation you need for each type of one-step equation.
下面的表格可以帮助你记住每种一步方程所需的逆运算。
| Equation | 方程 | Operation to undo | 要消去的运算 | Inverse step | 逆运算步骤 |
|---|---|---|
| x + a = b | add a | subtract a |
| x - a = b | subtract a | add a |
| ax = b | multiply by a | divide by a |
| x ÷ a = b | divide by a | multiply by a |
4. Solving Two-Step Equations | 解两步方程
from both sides: 2x = 8. Then undo the multiplication by dividing both sides by 2: x = 4.
两步方程包含两种运算,例如 2x +
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