SOLUTION: What are the roots of the equation x^2+9=0 I got x=+-3i,can someone explain?

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Question 120476: What are the roots of the equation x^2+9=0 I got x=+-3i,can someone explain?
Answer by tutor_paul(519) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E2%2B9=0
Get the x^2 term alone:
x%5E2=-9
Take the square root of both sides:
sqrt%28x%5E2%29=sqrt%28-9%29
Notice now you have to take the square root of a negative number of the right side. You can re-write this as:
x=sqrt%28-1%2A9%29
x=sqrt%28-1%29%2Asqrt%289%29
Note that i is defined as follows:
i=sqrt%28-1%29
So you can rewrite it as:
x=i%2Asqrt%289%29
the square root of 9 is +/-3. So your final answer is:
x=+/-3i
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Good Luck,
tutor_paul@yahoo.com