Question
Answer
$$(7-5i)\cdot(-6+10i)=-50i^2+100i-42$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(7-5i)\cdot(-6+10i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-42+70i+30i-50i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-50i^2+100i-42\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{7-5i}\right) $ by each term in $ \left( -6+10i\right) $. $$ \left( \color{blue}{7-5i}\right) \cdot \left( -6+10i\right) = -42+70i+30i-50i^2 $$ |
| ② | Combine like terms: $$ -42+ \color{blue}{70i} + \color{blue}{30i} -50i^2 = -50i^2+ \color{blue}{100i} -42 $$ |
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