Question

解方程组：x-y=3。2y+3(x-y)=11

Answer 1

该方程组可化简为x-y=3 ①
3x-y=11②
① 式乘3得：3x-3y=9③
用③式减①式得-2y=-2
所以y=1，代入①得x=4

Answer 2

x-y=3
2y+3(x-y)=11
=>2y+3=11 那么y=4 x=7

Answer 3

x-y=3
y=x-3
代入2y+3(x-y)=11
2y+3x-3y=11
3x-y=11
3x-(x-3)=11
2x=14
x=7
y=x-3=4