（x分之x-y乘y^2分之x+y）-（x^4y分之x^4-y^4）除（x^2分之x^2+y^2）明天就要交,

（x分之x-y乘y^2分之x+y）-（x^4y分之x^4-y^4）÷（x^2分之x^2+y^2）
=[(x-y)/x *(x+y)/y²-[(x⁴-y⁴)/x⁴y]/[(x²+y²)/x²]
=(x²-y²)/xy²-[(x²+y²)(x²-y²)/x⁴y]/[(x²+y²)/x²]
=(x²-y²)/xy²-(x²-y²)/x²y
=(x²-y²)/xy*(1/y-1/x)
=(x+y)(x-y)/xy*(x-y)/xy
=[(x+y)(x-y)²]/x²y²

(x-y)/x*(x+y)/y^2-(x^4-y^4)/(x^4y)÷(x^2+y^2)/x^2
=(x-y)(x+y)/(xy^2)-(x^2-y^2)(x^2+y^2)/(x^4y)*x^2/(x^2+y^2)
=(x^2-y^2)/(xy^2)-(x^2-y^2)/(x^2y)
=(x+y)(x-y)^3/(xy)^2

（x分之x-y乘y^2分之x+y）-（x^4y分之x^4-y^4）除（x^2分之x^2+y^2）
=（(x-y)/x *(x+y)/y^2）-（(x^2+y^2)/x^2）/（(x^4-y^4)/x^4y）
=（(x^2-y^2)/xy^2）-（(x^2+y^2)/x^2）*（x^4y/(x^2-y^2)(x^2+y^2)）
=（(x^2-y^2)/xy^2）-（（x^2y...