Question

已知x的平方+y的平方-8x+6y+25=0,求【x-y+x-y分之4xy】乘【x+y-x+y分之4xy】的值

Answer 1

(x^2-8x+16)+(y^2+6y+9)=(x-4)^2+(y+3)^2=0因两平方均非负,则两平方等于0.x=4,y=-3代入

(x-y+4xy/(x-y))(x+y-4xy/(x+y))=259