use elimination to solve each system of equations

题目

use elimination to solve each system of equations
例子:X- Y= 1 X + Y= 3 and 3x-y=26 -2x-y= -24

答案

利用消元法求解每个方程组1.x-y=1 (1)x+y=3 (2)解 (2)-1×(1)代替(2),原方程组化为x-y=1 (1)2y=2 (2)解得y=1代入(1)得x-1=1,x=2,故方程组的解为x=2,y=1.2.3x-y=26 (1)-2x-y=-24 (2)解 (2)-(-2/3)×(1)代替(2),原方程...