5(X-3Y)-6=2X+1,3(X+Y)=4(2X-Y)+16

问题描述:

5(X-3Y)-6=2X+1,3(X+Y)=4(2X-Y)+16

1. 解:1/2x+3y=-6…① 1/2x+y=2…②把①-②得 1/2x+3y-1/2x6(x+y)-4(2x-y)=16…②①同乘以12(分母3与4的积)得8(x-y)-12x

5(X-3Y)-6=2X+1,5x-15y-6=2x+13x-15y=7 (1)3(X+Y)=4(2X-Y)+163x+3y=8x-4y+165x-7y=-16 (2)(1)×5-(2)×3得15x-75y-15x+21y=35+48-64y=83y=-83/64带入(2)得5x+7×83/64=-165x=-1605/64x=-321/64...