Question

已知x=2008,y=2009.(x+y)×(x2+y2／x^4-y^4)= 要过程

Answer 1

(x+y)×(x2+y2／x^4-y^4)
=(x+y)×(x2+y2)／[(x2+y2)(x2-y2)]
=(x+y)×(x2+y2)／[(x2+y2)(x+y)(x-y)]
=1/(x-y)
=1/(2008-2009)
=-1

Answer 2

(x+y)×(x2+y2／x^4-y^4)
= (x+y)×(x²+y²／x^4-y^4)
= (x+y)×(x²+y²)／[(x²+y²)×(x²-y²)]
= (x+y)／(x²-y²)
= (x+y)／[(x+y)×(x-y)]
= 1／(x-y)
=-1