(a*5+b*5)-(a*3b*2+a*2b*3)=a^3(a^2-b^2)-b^3(a^2-b^2)=(a+b)(a^2+ab+b^2)(a-b)^2=(a+b)((a+(b/2))^2+(3/4)b^2)(a-b)^2当a+b>=0(a*5+b*5)-(a*3b*2+a*2b*3)>=0a*5+b*5>=a*3b*2+a*2b*3