1.x=2007,y=2008,求分式(x+y)(x²+y²)/x四次方-y四次方2.已知x/y=3,求x²+y²-xy/x²-y²的值

问题描述:

1.x=2007,y=2008,求分式(x+y)(x²+y²)/x四次方-y四次方
2.已知x/y=3,求x²+y²-xy/x²-y²的值