SOLUTION: I am reviewing for a test and I think I got the first 3 right. Can anybody check my answers? Also, I am having trouble on number 4. Thanks!!! 1. Solve. (x+18)(x-13)(x+16)>0

Question 558424: I am reviewing for a test and I think I got the first 3 right. Can anybody check my answers? Also, I am having trouble on number 4. Thanks!!!
1. Solve. (x+18)(x-13)(x+16)>0
I got �-18 < x < -16 or x>13
Am I right?
2.Multiply. (2√3-6√6)(5√3+15√6)
I got -510
Am I correct?
3. use the quadratic formula to solve the equation.x^2-x=-5
I got: x=1+i√19/2, 1-i√19/2
Am I correct?

4. find all the numbers for which the rational expression is undefined.
(s^3-6s)/(s^2-81)

Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
1. Solve. (x+18)(x-13)(x+16)>0
I got �-18 < x < -16 or x>13
Am I right?
It's correct.
-----------------
2.Multiply. (2√3-6√6)(5√3+15√6)
I got -510
(2√3-6√6)(5√3+15√6)
=
= -510
-------------------
-------------
3. use the quadratic formula to solve the equation.x^2-x=-5
I got: x=1+i√19/2, 1-i√19/2
Am I correct?
It's correct.
---------------
4. find all the numbers for which the rational expression is undefined.
(s^3-6s)/(s^2-81)
It's what makes the denominator zero.
s = -9, +9

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