Question 686530: How do you simplify 9 times the square root of negative 72
Answer by josh_jordan(263)   (Show Source):
You can put this solution on YOUR website! First, let's set this problem up in algebra form:
9 times the square root of negative 72 =
We need to get rid of the negative inside the root. To do this, first let's find out if there are any perfect squares that when multiplied by another number, give us 72.
Factors of 72: 1, 2, 3, 4, 6, 8, 9, 12, 24, 36, 72
Which of the above numbers is a perfect square? 36 is, because 6 x 6 = 36.
Now, what number muliplied by 36 gives us 72? 2.
So, 36 x 2 = 72
Now, we can remove both the 36 and the negative out of the root.
Remember that  , where the letter i represents an imaginary number.
So, the square root of 36 is 6, and the square root of -1 is i.
We are left with:
Which, when simplified, gives us our final answer:
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