Answers

2014-06-08T10:00:26+08:00
There's no square root for "-25" but the square root of 25 is 5.
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2014-06-08T10:08:59+08:00
Multiply the square root of 25 which is 5 by the square root of -1

square root of -1 is equal to an imaginary unit (i)

so i times 5 = 5i
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