Question

第十一题,答案已给出.

Answer 1

解11题

原式=[ (x-y)^4 -(x^4 -y^4) ]÷[ (x+y)(x-y) ]²

=[ (x-y)^4 -(x²+y²)(x+y)(x-y) ]÷[ (x+y)²(x-y)² ]

=(x-y)^4 ÷ [ (x+y)²(x-y)² ] -(x²+y²)(x+y)(x-y)÷[ (x+y)²(x-y)² ]

=(x-y)²/(x+y)² - (x²+y²)/[ (x+y)(x-y) ]

=(x-y)²/(x+y)² - (x²+y²)/(x²-y²)

正确答案应该选 C