SOLUTION: the domain and range of f(x) = 2x to the power of two plus 8x-1

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Question 1024212: the domain and range of f(x) = 2x to the power of two plus 8x-1
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Convert to vertex form,
f%28x%29=2x%5E2%2B8x-1
f%28x%29=2%28x%5E2%2B4x%29-1
f%28x%29=2%28x%5E2%2B4x%2B4%29-1-2%284%29
f%28x%29=2%28x%2B2%29%5E2-9
The vertex is at (-2,-9) and the coefficient of the quadratic term is positive so the parabola opens upwards and the vertex value is a minimum.
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So the domain is all real numbers and the range is [-9,infinity).
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