SOLUTION: find th values for which the rational expression is undefined -6+9x/x^3-8x^2+7

Question 774384: find th values for which the rational expression is undefined -6+9x/x^3-8x^2+7
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
find the values for which the rational expression is undefined -6+9x/x^3-8x^2+7
***
expression is undefined if denominator=0
x^3-8x^2+7=0
solve for x using rational roots theorem:
....0...|.....1.......-8........0.........7.....
....1...|.....1.......-7......-7.......-7 (1 is a root)
(x-1)(x^2-7x-7)
x^2-7x-7=0
solve by quadratic formula:

a=1, b=-7, c=-7
x≈0.8875
or
x=7.8875
expression is undefined if: x=1, 0.8875, or 7.885

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