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2014-11-22T08:21:57+08:00

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To answer complex answer, there is a given formula that:
i=√-1
i²=-1

Lets say for example:
(4+i)²
Do the square of binomial:
(4+i)(4+i)
=16+4i+4i+i²
Add all like terms:
16+8i+i²
Then since i²=-1, substitute the value:
16+8i-1
8i+15

We didn't do the 8i to 8√-1 because remember that there shuld be no negative number in square roots, so.... there:D

Hope this helps =)
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