a^3+3ab+b^3=(a+b)^3-3a^2*b-3b^2*a+3ab=(a+b)^3-3ab(a+b-1),然后把a,b带入,结果为1
^3表示立方,^2表示平方
即a+b=1
所以原式=(a+b)(a²-ab+b²)+3ab
=a²-ab+b²+3ab
=a²+2ab+b²
=(a+b)²
=1
a3次方+3ab+b3
=(a+b)(a^2-ab+b^2)+3ab
=a^2+2ab+b^2
=(a+b)^2
=1^2
=1
a+b=1
a³+3ab+b³
=a³+3ab(a+b)+b³
=a³+3a²b+3ab²+b³
=(a+b)³
=1