设a≠b,比较大小
详细过程
设a≠b,比较大小
详细过程
(a^4+b^4)(a^2+b^2)-(a^3+b^3)^2
=(a^6+b^6+a^4b^2+a^2b^4)-(a^6+b^6+2a^3b^3)
=a^4b^2+a^2b^4-2a^3b^2
=a^2b^2(a^2+b^2-2ab)
=a^2b^2(a-b)^2
∵a^2>=0,b^2>=0,(a-b)^2>0
∴(a^4+b^4)(a^2+b^2)-(a^3+b^3)^2=a^2b^2(a-b)^2>=0
∴(a^4+b^4)(a^2+b^2)>=(a^3+b^3)^2(取等a=0或b=0)