| $$ \begin{aligned}(3x+2)^3& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}27x^3+54x^2+36x+8\end{aligned} $$ | |
| ① | Find $ \left(3x+2\right)^3 $ using formula $$ (A + B) = A^3 + 3A^2B + 3AB^2 + B^3 $$where $ A = 3x $ and $ B = 2 $. $$ \left(3x+2\right)^3 = \left( 3x \right)^3+3 \cdot \left( 3x \right)^2 \cdot 2 + 3 \cdot 3x \cdot 2^2+2^3 = 27x^3+54x^2+36x+8 $$ |