| $$ \begin{aligned}(x^2+x)^3& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}x^6+3x^5+3x^4+x^3\end{aligned} $$ | |
| ① | Find $ \left(x^2+x\right)^3 $ using formula $$ (A + B) = A^3 + 3A^2B + 3AB^2 + B^3 $$where $ A = x^2 $ and $ B = x $. $$ \left(x^2+x\right)^3 = \left( x^2 \right)^3+3 \cdot \left( x^2 \right)^2 \cdot x + 3 \cdot x^2 \cdot x^2+x^3 = x^6+3x^5+3x^4+x^3 $$ |