Equations
方程
An equation says two things are equal. In this lesson you will learn what an equation is, how to solve one-step and two-step equations, and how to check your answers.
方程表示兩邊相等。在這一課，你會學習甚麼是方程、怎樣解一步和兩步方程，以及怎樣驗算。
1 · What is an equation?
甚麼是方程？
An equation is a statement that two things are equal, shown with an equals sign. Think of it as a balance scale: both sides must weigh the same. x + 3 = 7 means "x plus 3 balances with 7".
方程是表示兩邊相等的式子，用等號表示。把它想成天平：兩邊必須一樣重。x + 3 = 7 是指「x 加 3 與 7 平衡」。
2 · One-step equations
一步方程
To solve an equation, we find the value of the unknown. We use inverse operations. In x + 3 = 7, subtract 3 from both sides: x = 7 − 3 = 4.
解方程就是找出未知數的值。我們用逆運算。在 x + 3 = 7 中，兩邊同時減 3：x = 7 − 3 = 4。
The inverse of addition is subtraction; the inverse of multiplication is division.
加法的逆運算是減法；乘法的逆運算是除法。
3 · Two-step equations
兩步方程
For 2x + 3 = 11, we undo the operations in reverse order. First subtract 3: 2x = 8. Then divide by 2: x = 4.
對於 2x + 3 = 11，我們以相反次序逆運算。先減 3：2x = 8。再除以 2：x = 4。
4 · Checking your answer
驗算
Always check your answer by putting it back into the equation. For x = 4 in 2x + 3 = 11: 2 × 4 + 3 = 8 + 3 = 11. Correct!
一定要把答案代回方程來驗算。把 x = 4 代入 2x + 3 = 11：2 × 4 + 3 = 8 + 3 = 11。正確！
5 · Quick check
小測驗