Tap the blue circles to see an explanation.
$$ \begin{aligned}(x-6)(x-3)^2& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}(x-6)(x^2-6x+9) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}x^3-6x^2+9x-6x^2+36x-54 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}x^3-12x^2+45x-54\end{aligned} $$ | |
① | Find $ \left(x-3\right)^2 $ using formula. $$ (A - B)^2 = \color{blue}{A^2} - 2 \cdot A \cdot B + \color{red}{B^2} $$where $ A = \color{blue}{ x } $ and $ B = \color{red}{ 3 }$. $$ \begin{aligned}\left(x-3\right)^2 = \color{blue}{x^2} -2 \cdot x \cdot 3 + \color{red}{3^2} = x^2-6x+9\end{aligned} $$ |
② | Multiply each term of $ \left( \color{blue}{x-6}\right) $ by each term in $ \left( x^2-6x+9\right) $. $$ \left( \color{blue}{x-6}\right) \cdot \left( x^2-6x+9\right) = x^3-6x^2+9x-6x^2+36x-54 $$ |
③ | Combine like terms: $$ x^3 \color{blue}{-6x^2} + \color{red}{9x} \color{blue}{-6x^2} + \color{red}{36x} -54 = x^3 \color{blue}{-12x^2} + \color{red}{45x} -54 $$ |