Question
Answer
$$(3i-5)^2-11=9i^2-30i+14$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(3i-5)^2-11& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}9i^2-30i+25-11 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}9i^2-30i+14\end{aligned} $$ | |
| ① | Find $ \left(3i-5\right)^2 $ using formula. $$ (A - B)^2 = \color{blue}{A^2} - 2 \cdot A \cdot B + \color{red}{B^2} $$where $ A = \color{blue}{ 3i } $ and $ B = \color{red}{ 5 }$. $$ \begin{aligned}\left(3i-5\right)^2 = \color{blue}{\left( 3i \right)^2} -2 \cdot 3i \cdot 5 + \color{red}{5^2} = 9i^2-30i+25\end{aligned} $$ |
| ② | Combine like terms: $$ 9i^2-30i+ \color{blue}{25} \color{blue}{-11} = 9i^2-30i+ \color{blue}{14} $$ |
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