Tap the blue circles to see an explanation.
$$ \begin{aligned}(x-4)(x+3)(2x-1)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}(x^2+3x-4x-12)(2x-1) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}(x^2-x-12)(2x-1) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}2x^3-x^2-2x^2+x-24x+12 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle4}{\textcircled {4}} } }}}2x^3-3x^2-23x+12\end{aligned} $$ | |
① | Multiply each term of $ \left( \color{blue}{x-4}\right) $ by each term in $ \left( x+3\right) $. $$ \left( \color{blue}{x-4}\right) \cdot \left( x+3\right) = x^2+3x-4x-12 $$ |
② | Combine like terms: $$ x^2+ \color{blue}{3x} \color{blue}{-4x} -12 = x^2 \color{blue}{-x} -12 $$ |
③ | Multiply each term of $ \left( \color{blue}{x^2-x-12}\right) $ by each term in $ \left( 2x-1\right) $. $$ \left( \color{blue}{x^2-x-12}\right) \cdot \left( 2x-1\right) = 2x^3-x^2-2x^2+x-24x+12 $$ |
④ | Combine like terms: $$ 2x^3 \color{blue}{-x^2} \color{blue}{-2x^2} + \color{red}{x} \color{red}{-24x} +12 = 2x^3 \color{blue}{-3x^2} \color{red}{-23x} +12 $$ |