SOLUTION: Use completing the square to describe the graph of f(x) =8-16x-x^2. Support your answers graphically.

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Question 766280: Use completing the square to describe the graph of f(x) =8-16x-x^2. Support your answers graphically.
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
Given is f%28x%29=-x%5E2-16x%2B8.

factor a -1:
-1%28x%5E2%2B16x-8%29

Determine the missing square term:
%2816%2F2%29%5E2=64

Add and subtract 64 inside the grouped polynomial factor:
%28-1%29%28x%5E2%2B16x%2B64-64-8%29

Factor the desired square term existing inside the parentheses:
%28-1%29%28%28x%2B8%29%5E2-72%29.... and take care of a little bit more of the arithmetic..

Remultiply:
-%28x%2B8%29%5E2%2B72

Function ready to graph is f%28x%29=-%28x%2B8%29%5E2%2B72

graph%28450%2C450%2C-15%2C15%2C-5%2C80%2C-%28x%2B8%29%5E2%2B72%29