用加减法解方程组2(X+Y)-3(X-Y)=36;3(X+Y)+2(X-2Y)=-12这道题是我乘过的，原题是(X+Y)/3-(X-Y)/2=36;3(X+Y)+2(X-2Y)=-12
网友回答
由(1)得2x+2y-3x+3y=36
-x+5y=36 (3)
由(2)得3x+3y+2x-4y=-12
5x-y=-12 (4)
(3)×5+(4)得
24y=168
y=7把y=7代入(3)得
-x+35=36
∴x=-1∴x=-1y=7======以下答案可供参考======
供参考答案1:
(2)*2-(1)*3
4(X-2Y)+9(X-Y)=-24-108, 4X-8Y+9X-9Y=-132, 13X-17Y=-132 ...(3)
(1): 2X+2Y-3X+3Y=36, X=5Y-36 ....(4)
代入(3): 13(5Y-36)-17Y=-132, 65Y-468-17Y=-132, 48Y=336, Y=7
代入(4): X=5*7-36=-1
所以 X=-1, Y=7