algebra · worked example

Solve 聯立方程式:2x+y=7 與 x-y=2

Method: 加減消去法. Verified step-by-step solution with our free AI math solver.
Problem

{2x+y=7xy=2\begin{cases} 2x + y = 7 \\ x - y = 2 \end{cases}

Step-by-step solution

  1. 將兩個方程式相加以消去 yy(2x+y)+(xy)=7+2(2x + y) + (x - y) = 7 + 2,因此 3x=93x = 9

  2. 解出 xxx=3x = 3

  3. 代回任一方程式。使用第二個式子:3y=23 - y = 2,因此 y=1y = 1

  4. 在第一個式子中驗證:2(3)+1=72(3) + 1 = 7。✓

Answer

(x,y)=(3,1)(x, y) = (3, 1)

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