Question

怎么算a+b=a的平方?

Answer 1

(a-b)³

=(a-b)(a-b)²

=(a-b)(a²-2ab+b²)

=a(a²-2ab+b²)-b(a²-2ab+b²)

=a³-2a²b+ab²-a²b+2ab²-b³

=a³-3a²b+3ab²-b³

1、a+b的三次方公式：

(a+b)³

=(a+b)²(a+b)

=(a²+2ab+b²)(a+b)

=a(a²+2ab+b²)+b(a²+2ab+b²)

=a³+2a²b+ab²+a²b+2ab²+b³

=a³+3a²b+3ab²+b³

2、a+b的四次方公式：

(a+b)^4

=(a+b)³(a+b)

=(a³+3a²b+3ab²+b³)(a+b)

=a(a³+3a²b+3ab²+b³)+b(a³+3a²b+3ab²+b³)

=a^4+4a³b+6a²b²+4ab³+b^4