SOLUTION: Sqrt of -15 times the sqrt of -5

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Question 963738: Sqrt of -15 times the sqrt of -5
Found 3 solutions by lwsshak3, ikleyn, greenestamps:
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Sqrt of -15 times the sqrt of -5
√15*√-1*√5*√-1=-√75=-5√3

Answer by ikleyn(53891) About Me  (Show Source):
You can put this solution on YOUR website!
.
Sqrt of -15 times the sqrt of -5
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The "solution" in the post by @lwsshak3 is incorrect and makes no sense.

A correct answer is as follows:

        - in real numbers, sqrt%28-15%29 and sqrt%28-5%29 are not defined, so it makes no sense (prohibited) to manipulate with them.

        - in complex numbers, square root always has two values for a non-zero argument.

So, when somebody asks what is sqrt%28-15%29%2Asqrt%28-5%29, he/she should determine/define first,
which of two possible values for each sqrt%28-15%29 and sqrt%28-5%29 does he/she means.

Only after that the answer can be done.



Answer by greenestamps(13358) About Me  (Show Source):
You can put this solution on YOUR website!


%28sqrt%28-15%29%29%2A%28sqrt%28-5%29%29

The rule %28sqrt%28a%29%29%2A%28sqrt%28b%29%29=sqrt%28ab%29 does NOT hold if both a and b are negative.



ANSWER: -5sqrt%283%29