已知x²+2xy-8y²=0(y≠0),求(x-y)/(x+y)的值

已知x²+2xy-8y²=0(y≠0),求(x-y)/(x+y)的值
已知x²+2xy-8y²=0(y≠0),求(x-y)/(x+y)的值

已知x²+2xy-8y²=0(y≠0),求(x-y)/(x+y)的值
x²+2xy-8y²=0(y≠0),
等价于（x+4y）（x-2y）=0
所以x=-4y或x=2y
(x-y)/(x+y)
=-5y/-3y
= 5/3
或
(x-y)/(x+y)
=y/3y
=1/3