Question
Answer
$$(4i+9)(9i+9)=36i^2+117i+81$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(4i+9)(9i+9)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}36i^2+36i+81i+81 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}36i^2+117i+81\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{4i+9}\right) $ by each term in $ \left( 9i+9\right) $. $$ \left( \color{blue}{4i+9}\right) \cdot \left( 9i+9\right) = 36i^2+36i+81i+81 $$ |
| ② | Combine like terms: $$ 36i^2+ \color{blue}{36i} + \color{blue}{81i} +81 = 36i^2+ \color{blue}{117i} +81 $$ |
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