a^5 + b^5 - a^2*b^3 - a^3*b^2
= a^2(a^3 - b^3) + b^2(b^3 - a^3)
= (a^2 - b^2)(a^3 - b^3)
= (a+b)(a-b)(a-b)(a^2+ab+b^2)
= (a-b)^2 * (a+b) * (a^2+ab+b^2)
a,b不相等,所以上式恒大于0
a^5 + b^5 - a^2*b^3 - a^3*b^2
= a^2(a^3 - b^3) + b^2(b^3 - a^3)
= (a^2 - b^2)(a^3 - b^3)
= (a+b)(a-b)(a-b)(a^2+ab+b^2)
= (a-b)^2 * (a+b) * (a^2+ab+b^2)
a,b不相等,所以上式恒大于0