已知x²－y²＝－1,x+y＝0.5,求x－y的值

已知x²－y²＝－1,x+y＝0.5,求x－y的值

（x-y)*(x+y)=-1,把x+y=0.5带入,0.5*（x-y)=-1,x-y=-2

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

-2

x²－y²=(x+y)(x－y)=-1;
x+y＝0.5;
x－y=-1/0.5=-2