Question
Answer
$$2i\cdot(5-2i)=10i+4$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}2i\cdot(5-2i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}10i-4i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}10i+4\end{aligned} $$ | |
| ① | Multiply $ \color{blue}{2i} $ by $ \left( 5-2i\right) $ $$ \color{blue}{2i} \cdot \left( 5-2i\right) = 10i-4i^2 $$ |
| ② | $$ -4i^2 = -4 \cdot (-1) = 4 $$ |
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