Tap the blue circles to see an explanation.
| $$ \begin{aligned}(x-1)^2(x-10)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}(x^2-2x+1)(x-10) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}x^3-10x^2-2x^2+20x+x-10 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}x^3-12x^2+21x-10\end{aligned} $$ | |
| ① | Find $ \left(x-1\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}{ 1 }$. $$ \begin{aligned}\left(x-1\right)^2 = \color{blue}{x^2} -2 \cdot x \cdot 1 + \color{red}{1^2} = x^2-2x+1\end{aligned} $$ |
| ② | Multiply each term of $ \left( \color{blue}{x^2-2x+1}\right) $ by each term in $ \left( x-10\right) $. $$ \left( \color{blue}{x^2-2x+1}\right) \cdot \left( x-10\right) = x^3-10x^2-2x^2+20x+x-10 $$ |
| ③ | Combine like terms: $$ x^3 \color{blue}{-10x^2} \color{blue}{-2x^2} + \color{red}{20x} + \color{red}{x} -10 = x^3 \color{blue}{-12x^2} + \color{red}{21x} -10 $$ |