Question

解方程组{(x+2)(y+1)=(x-5)(y-1) x(4+y)=-y(8-x),

Answer 1

(x+2)(y+1) = (x-5)(y-1)

整理得

xy+x+2y+2=xy-x-5y+5

xy+x+2y-xy+x+5y=5-2

2x+7y=3 (1)

整理得

x(4+y) = -y(8-x)

4x+xy=-8y+xy

4x+xy-xy=-8y

4x=-8y

x=-2y (2)

把（2）带入（1）得

2*(-2y)+7y=3

-4y+7y=3

3y=3

y=1

把y=1带入（2）得

x=-2y

x=-2*1

x=-2

即

x=-2

y=1