七下两道二元一次方程{4(x-y)+2y+5=0{3x-4y=5{6(x-y)-2(x+y)=14{3(x-y)+(x+y)=5

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七下两道二元一次方程{4(x-y)+2y+5=0{3x-4y=5{6(x-y)-2(x+y)=14{3(x-y)+(x+y)=5
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七下两道二元一次方程{4(x-y)+2y+5=0{3x-4y=5{6(x-y)-2(x+y)=14{3(x-y)+(x+y)=5
七下两道二元一次方程
{4(x-y)+2y+5=0
{3x-4y=5
{6(x-y)-2(x+y)=14
{3(x-y)+(x+y)=5

七下两道二元一次方程{4(x-y)+2y+5=0{3x-4y=5{6(x-y)-2(x+y)=14{3(x-y)+(x+y)=5
{4(x-y)+2y+5=0 化简得: 2y=4x+5
代入到3x-2*2y=5中 得3x-2*(4x+5)=5
化简得 -5x=15 x=-3
代x=-3入到2y=4x+5中得2y=-7 y=-7/2
方程组的解为:x=-3;y=-7/2
6(x-y)-2(x+y)=14 化简得 4x-8y=14
3(x-y)+(x+y)=5 化简得 4x-2y=5
两式相减得: 6y=-9 y=-3/2
代y=-3/2 入4x-2y=5中得 4x-3=5 x=1/2
解为: x=1/2 y=-3/2
x=1/2