Question

chứng minh:

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

Answer 1

\(\left(a+b\right)\left(a^2-ab+b^2\right)-\left(a-b\right)\left(a^2+ab+b^2\right)\)

\(=\left(a^3+b^3\right)-\left(a^3-b^3\right)\)

\(=a^3+b^3-a^3+b^3\)

`=2b^3`