Question

(x+y)分之(x^2+2xy+y^2)乘 （x^2+y^2)除 (y-1)分之(x^4-y^4)

Answer 1

原式=(x+y)/(x+y)^2*(x^4-y^4)(x^2+y^2)/(y-1)

=[2*(x^2+y^2)(y-1)(x+y)]/[(x+y)^2(y^2+x^2)(x+y)(x-y)]

=2*(y-1)/(x+y)^2(x-y)