解方程组2(x+y)-(x-y)=3且(x+y)-2(x-y)=1

3x-4(x-y)=2且2x-3y=1

2(x+y)-(x-y)=3且(x+y)-2(x-y)=1

3x-4(x-y)=2,-x+4y=2
2x-3y=1
5y=5,y=1
x=4y-2=2

2(x+y)-(x-y)=3
(x+y)-2(x-y)=1
3(x-y)=1,
x-y=1/3
x+y=5/3
2x=2,x=1
y=2/3
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第1个回答  2014-03-13
1.3x-4(x-y)=2
2x-3y=1
解:有1式得4y-x=2 即:2x-8y=-4
所以5y=5
y=1,x=2
2,2(x+y)-(x-y)=3
(x+y)-2(x-y)=1
解:有1式得 x+3y=3
3y-2x=1
所以-x=4,
x=-4
y=7/3