计算[-x^2y^3/3(x+y)]^4*(x^2-y^2/x^2y^2)^3
问题描述：
计算[-x^2y^3/3(x+y)]^4*(x^2-y^2/x^2y^2)^3
答
[-x^2y^3/3(x+y)]^4*(x^2-y^2/x^2y^2)^3
= -[ x^8y^12/x^6y^6]* [(x^2-y^2)^3/(x+y)^4] / 81
= -x^2y^6*(x-y)^3 / 81(x+y)