Answer
$$(1-5i)\cdot(5+6i)=-30i^2-19i+5$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(1-5i)\cdot(5+6i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}5+6i-25i-30i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-30i^2-19i+5\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{1-5i}\right) $ by each term in $ \left( 5+6i\right) $. $$ \left( \color{blue}{1-5i}\right) \cdot \left( 5+6i\right) = 5+6i-25i-30i^2 $$ |
| ② | Combine like terms: $$ 5+ \color{blue}{6i} \color{blue}{-25i} -30i^2 = -30i^2 \color{blue}{-19i} +5 $$ |
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