Question
Answer
$$(r\cdot5+2r\cdot20)(-r-5)=-45r^2-225r$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(r\cdot5+2r\cdot20)(-r-5)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}(5r+40r)(-r-5) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}45r(-r-5) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}-45r^2-225r\end{aligned} $$ | |
| ① | $$ 2 r \cdot 20 = 40 r $$ |
| ② | Combine like terms: $$ \color{blue}{5r} + \color{blue}{40r} = \color{blue}{45r} $$ |
| ③ | Multiply $ \color{blue}{45r} $ by $ \left( -r-5\right) $ $$ \color{blue}{45r} \cdot \left( -r-5\right) = -45r^2-225r $$ |
This page was created using
Complex Expression calculator