Question
Answer
$$(7x-1)(x+2)-(x+4)=7x^2+12x-6$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(7x-1)(x+2)-(x+4)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}7x^2+14x-x-2-(x+4) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}7x^2+13x-2-(x+4) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}7x^2+13x-2-x-4 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle4}{\textcircled {4}} } }}}7x^2+12x-6\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{7x-1}\right) $ by each term in $ \left( x+2\right) $. $$ \left( \color{blue}{7x-1}\right) \cdot \left( x+2\right) = 7x^2+14x-x-2 $$ |
| ② | Combine like terms: $$ 7x^2+ \color{blue}{14x} \color{blue}{-x} -2 = 7x^2+ \color{blue}{13x} -2 $$ |
| ③ | Remove the parentheses by changing the sign of each term within them. $$ - \left( x+4 \right) = -x-4 $$ |
| ④ | Combine like terms: $$ 7x^2+ \color{blue}{13x} \color{red}{-2} \color{blue}{-x} \color{red}{-4} = 7x^2+ \color{blue}{12x} \color{red}{-6} $$ |
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