Question
Answer
$$3x(2x-4)-x(x+5)=5x^2-17x$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}3x(2x-4)-x(x+5)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}6x^2-12x-(x^2+5x) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}6x^2-12x-x^2-5x \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}5x^2-17x\end{aligned} $$ | |
| ① | Multiply $ \color{blue}{3x} $ by $ \left( 2x-4\right) $ $$ \color{blue}{3x} \cdot \left( 2x-4\right) = 6x^2-12x $$Multiply $ \color{blue}{x} $ by $ \left( x+5\right) $ $$ \color{blue}{x} \cdot \left( x+5\right) = x^2+5x $$ |
| ② | Remove the parentheses by changing the sign of each term within them. $$ - \left( x^2+5x \right) = -x^2-5x $$ |
| ③ | Combine like terms: $$ \color{blue}{6x^2} \color{red}{-12x} \color{blue}{-x^2} \color{red}{-5x} = \color{blue}{5x^2} \color{red}{-17x} $$ |
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