SOLUTION: how do you do a problem like this x3+2x2-8x-16=0...its wanting me to list all possible rational roots and then find any actual rational roots.

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Question 362572: how do you do a problem like this x3+2x2-8x-16=0...its wanting me to list all possible rational roots and then find any actual rational roots.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Look at the factors of the leading coefficient, 1 and the constant coefficient 16.
q : Factors of 1 : {1}
p : Factors of 16 : {1,2,4,8,16}
Possible zeros are of the form p%2Fq
{1/1,2/1,4/1,8/1,16/1} and their negative counterparts,
{-1,-2,-4,-8,-16}
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graph%28300%2C300%2C-10%2C10%2C-10%2C10%2Cx%5E3%2B2x%5E2-8x-16%29
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Looks like x=-2 is a possible candidate.
Verify using the equation.
f%28-2%29=%28-2%29%5E3%2B2%28-2%29%5E2-8%28-2%29-16
f%28-2%29=-8%2B8%2B16-16
f%28-2%29=0
The other two roots are therefore irrational.