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

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

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

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

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