sqrt question

[Namir]

(04-06-2017 03:25 PM)KeithB Wrote:  I just saw one of those "Do you think you know the answer" things.

"What is the result of sqrt(-4)*sqrt(-9)"

If you look at it one way there is no answer.
If you combine the operations: sqrt(-4)*sqrt(-9) = sqrt(-4*-9) = sqrt(36) = 6

otherwise:
sqrt(-4) = 2i, sqrt(-9) = 3i, 2i*3i = -6, since i*i = -1.

Which do you think is the answer they wanted?

I guess whether you first combine the values in the square roots or not makes a difference!