Question

已知x^2+y^2-2x+4y+5=0,求(x^4-y^4)/(x^2-2xy+y^2)*（x-y

Answer 1

由题得：(x-1)²+(y+2)²=0

所以,x=1,y=-2

所以原式=(x^2+y^2)(x+y)(x-y)/(x-y)^2 * (x-y)/y(x+y)=(x^2+y^2)/y=5/2