若a+b=m,ab=n,求a4+b4的值.-数学

题目简介

若a+b=m,ab=n,求a4+b4的值.-数学

题目详情

若a+b=m,ab=n,求a4+b4的值.
题型:解答题难度:中档来源:不详

答案

a4+b4=(a2+b2)2-2a2b2,
=[(a+b)2-2ab]2-2a2b2,
=(m2-2n)2-2n2,
=m4-4m2n+4n2-2n2,
=m4-4m2n+2n2.

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