Question
Answer
$$(5x)^3(x-3i)=-375ix^3+125x^4$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(5x)^3(x-3i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}125x^3(x-3i) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}125x^4-375ix^3 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}-375ix^3+125x^4\end{aligned} $$ | |
| ① | $$ \left( 5x \right)^3 = 5^3x^3 = 125x^3 $$ |
| ② | Multiply $ \color{blue}{125x^3} $ by $ \left( x-3i\right) $ $$ \color{blue}{125x^3} \cdot \left( x-3i\right) = 125x^4-375ix^3 $$ |
| ③ | Combine like terms: $$ -375ix^3+125x^4 = -375ix^3+125x^4 $$ |
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