SOLUTION: Could someone help me with this one; sqrt(-25)sqrt(-9) My answer was 15, but it got marked wrong on my test, but sqrt(-25)=-5 and sqrt(-9)=-3 and -5*-3=15 so I dont really unde

Question 186786: Could someone help me with this one;
sqrt(-25)sqrt(-9)
My answer was 15, but it got marked wrong on my test, but sqrt(-25)=-5 and sqrt(-9)=-3 and -5*-3=15 so I dont really understand why its wrong.
Found 2 solutions by jim_thompson5910, D13E12:
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
Note: and since you CANNOT take the square root of a negative number. Instead, we denote the value where 'i' is an imaginary number.

So...

This means that

So you were off by a sign.
Answer by D13E12(2) (Show Source): You can put this solution on YOUR website!
Sqrt(-25)= 5i, where i is the sqrt(-1)
sqrt(-9) = 3i , i= sqrt(-1)
now sqrt(-25)sqrt(-9) = 5i*3i=15 (i)^2=15*-1=-15
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