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41 votes
41 votes
Perform the indicated operation and express your answer in the form

Perform the indicated operation and express your answer in the form-example-1
User Dave Cameron
by
2.1k points

1 Answer

10 votes
10 votes

Ok, so

Here we have the following expression:


\sqrt[]{(5+12i)(12i-5)}

We could multiply the brackets:


\sqrt[]{60i-25+144i^2-60i}

And then simplify:


\sqrt[]{144i^2-25}

Remember that


\begin{gathered} i=\sqrt[]{-1} \\ i^2=-1 \end{gathered}

So if we replace:


\begin{gathered} \sqrt[]{144(-1)-25} \\ \sqrt[]{-144-25} \\ \sqrt[]{-169} \end{gathered}

We could rewrite the last expression:


\sqrt[]{-169}=\sqrt[]{-1}\cdot\sqrt[]{169}

And that is:


\sqrt[]{-1}\cdot\sqrt[]{169}=13i

So the answer is 13i.

Written with the form a + bi:

This is 0 + 13i , which is 13i.

User Clare Barrington
by
2.7k points
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