1
=(a+b)^3
=a^3+b^3+3a^b+3ab^2
=a^3+b^3+3ab(a+b)
=a^3+b^3+3ab
证毕sorry ,(a+b)^3-3ab=a^3+b^3,您反了那你的题显然错了例如a=1/2,b=1/2a^3=1/8b^3=1/83ab=3/4a^3+b^3-3ab=1/8+1/8-3/4=-1/2≠1显然应该是+3ab才对~