Question

已知a^3+3ab+b^3=1,求a+b的值

Answer 1

已知a+b=1,求a^3+3ab+b^3的值 吧
a^3+3ab+b^3
=(a^3+b^3)+3ab
=(a+b)(a^2-ab+b^2)+3ab
=1*(a^2-ab+b^2)+3ab
=a^2+2ab+b^2
=(a+b)^2
=1^2
=1.