已知x²－y²＝－1,x+y＝0.5,求x－y的值

网友回答

（x-y)*(x+y)=-1,把x+y=0.5带入,0.5*（x-y)=-1,x-y=-2
======以下答案可供参考======
供参考答案1:
x²－y²＝－1
(x+y)(x-y)=-1，x-y=-1/(x+y)
x+y＝0.5,所以x-y=-1/0.5=-2
供参考答案2:
-2供参考答案3:
x²－y²=(x+y)(x－y)=-1;
x+y＝0.5;
x－y=-1/0.5=-2