已知:-2=x(x-1)-(x的平方-y),①求x-y的值 ②若(x-1)(y+3)<xy,求x的取值范围.
问题描述:
已知:-2=x(x-1)-(x的平方-y),①求x-y的值 ②若(x-1)(y+3)<xy,求x的取值范围.
答
x(x-1)-(x的平方-y)=-2
x²-x-x²+y=-2
∴-x+y=-2
x-y=2
(x-1)(y+3)