Question
Answer
$$15i(-i-1)=-15i+15$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}15i(-i-1)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-15i^2-15i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}15-15i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}-15i+15\end{aligned} $$ | |
| ① | Multiply $ \color{blue}{15i} $ by $ \left( -i-1\right) $ $$ \color{blue}{15i} \cdot \left( -i-1\right) = -15i^2-15i $$ |
| ② | $$ -15i^2 = -15 \cdot (-1) = 15 $$ |
| ③ | Combine like terms: $$ -15i+15 = -15i+15 $$ |
This page was created using
Complex Expression calculator