用代入法解下列方程组(一题5分哦,快来!）⑴2(x+y)-(x-y)=3(x+y)-2(x-y)=1

Question

用代入法解下列方程组(一题5分哦,快来!）
⑴2(x+y)-(x-y)=3
(x+y)-2(x-y)=1

Answer 1

2(x+y)-(x-y)=3 ,x+3y=3,x=3-3y
(x+y)-2(x-y)=1,-x+3y=1
把x=3-3y代入-x+3y=1:
-(3-3y)+3y=1
6y-3=1
6y=4
y=2/3
x=3-3y=1
解为:x=1,y=2/3