SOLUTION: Find f(15) for f (x) = x^2-4/8-x^3

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Question 156274: Find f(15) for f (x) = x^2-4/8-x^3
Answer by orca(409) About Me  (Show Source):
You can put this solution on YOUR website!
Note that the expression %28x%5E2-4%29%2F%288-x%5E3%29 can be simplified.
%28x%5E2-4%29%2F%288-x%5E3%29
=%28x%5E2-4%29%2F%28-%28x%5E3-8%29%29 (As 8 - x^3 = -(x^3 - 8))
=-%28x%5E2-4%29%2F%28x%5E3-8%29
=-%28x%5E2-2%5E2%29%2F%28x%5E3-2%5E3%29
=-%28%28x%2B2%29%28x-2%29%29%2F%28%28x-2%29%28x%5E2%2B2x%2B4%29%29
=-%28%28x%2B2%29cross%28%28x-2%29%29%29%2F%28cross%28%28x-2%29%29%28x%5E2%2B2x%2B4%29%29
=-%28x%2B2%29%2F%28x%5E2%2B2x%2B4%29
Now substitute x = 15 into the above expression to find f(15).
f%2815%29=+-%2815%2B2%29%2F%2815%5E2%2B2%2A15%2B4%29
=-17%2F259