Question

8+x³/27 =2³+(x/3)³ =(2+x/3)(4-2x/3+x²/9) 是什么依据

Answer 1

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

推导如下

a^3+b^3

=a^3+a^2b-a^2b-ab^2+ab^2+b^3

=a^2(a+b)-ab(a+b)+b^2(a+b)

=(a+b)(a^2-ab+b^2)