a+b+c=0,证明a^3+b^3+c^3=3abc

来源:学生作业学帮网 编辑:学帮网 时间:2024/05/16 12:26:23

a+b+c=0,证明a^3+b^3+c^3=3abc

c= -(a+b)
a^3+b^3+c^3
=a^3+b^3-(a+b)^3
=a^3+b^3-(a^3+3a^2b+3ab^2+b^3)
= -(3a^2b+3ab^2)
= -3ab(a+b)
=3abc