Question

x*x+2x-y*y+6y-8=0,x+y不等于2,求x-y的值

Answer 1

x²+2x-y²+6y-8=0

x²+2x+1-(y²-6y+9)=0

(x+1)²-(y-3)²=0

(x+1)²=(y-3)²

x+1=±(y-3)

x+1=y-3

x-y=-4

x+1=-(y-3)

x+y=2(舍)

∴x-y=-4