$$ \begin{aligned}(2x+5)^3& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}8x^3+60x^2+150x+125\end{aligned} $$ | |
① | Find $ \left(2x+5\right)^3 $ using formula $$ (A + B) = A^3 + 3A^2B + 3AB^2 + B^3 $$where $ A = 2x $ and $ B = 5 $. $$ \left(2x+5\right)^3 = \left( 2x \right)^3+3 \cdot \left( 2x \right)^2 \cdot 5 + 3 \cdot 2x \cdot 5^2+5^3 = 8x^3+60x^2+150x+125 $$ |