Question 558424
1. Solve. (x+18)(x-13)(x+16)>0
I got …-18 < x < -16 or x>13
Am I right?
It's correct.
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2.Multiply. (2&#8730;3-6&#8730;6)(5&#8730;3+15&#8730;6)
I got -510
(2&#8730;3-6&#8730;6)(5&#8730;3+15&#8730;6)
= {{{10*3 + 30sqrt(18) -30sqrt(18) -90*6}}}
= -510
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3. use the quadratic formula to solve the equation.x^2-x=-5
I got: x=1+i&#8730;19/2, 1-i&#8730;19/2
Am I correct?
It's correct.
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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