Tap the blue circles to see an explanation.
| $$ \begin{aligned}x(x+1)(x-2)(x-3)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}(x^2+x)(x-2)(x-3) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}(x^3-2x^2+x^2-2x)(x-3) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}(x^3-x^2-2x)(x-3) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle4}{\textcircled {4}} } }}}x^4-3x^3-x^3+3x^2-2x^2+6x \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle5}{\textcircled {5}} } }}}x^4-4x^3+x^2+6x\end{aligned} $$ | |
| ① | Multiply $ \color{blue}{x} $ by $ \left( x+1\right) $ $$ \color{blue}{x} \cdot \left( x+1\right) = x^2+x $$ |
| ② | Multiply each term of $ \left( \color{blue}{x^2+x}\right) $ by each term in $ \left( x-2\right) $. $$ \left( \color{blue}{x^2+x}\right) \cdot \left( x-2\right) = x^3-2x^2+x^2-2x $$ |
| ③ | Combine like terms: $$ x^3 \color{blue}{-2x^2} + \color{blue}{x^2} -2x = x^3 \color{blue}{-x^2} -2x $$ |
| ④ | Multiply each term of $ \left( \color{blue}{x^3-x^2-2x}\right) $ by each term in $ \left( x-3\right) $. $$ \left( \color{blue}{x^3-x^2-2x}\right) \cdot \left( x-3\right) = x^4-3x^3-x^3+3x^2-2x^2+6x $$ |
| ⑤ | Combine like terms: $$ x^4 \color{blue}{-3x^3} \color{blue}{-x^3} + \color{red}{3x^2} \color{red}{-2x^2} +6x = x^4 \color{blue}{-4x^3} + \color{red}{x^2} +6x $$ |