SOLUTION: What is the equation of the axis of symmetry of the graph y=4x^2-5x+16

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Question 853683: What is the equation of the axis of symmetry of the graph y=4x^2-5x+16
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
More than one way to find it; although both are based on Completing the Square.
One way is find the two roots using general solution to a quadratic equation. The axis of symmetry for this equation will be in the exact middle of the two roots.

Discriminant: 25-4*4*16=-231=-3*7*11

highlight%28x=%285%2B-+i%2Asqrt%28231%29%29%2F8%29, the zeros or roots.
The exact middle is the AVERAGE of those.
-
%281%2F2%29%28%285%2F8%29%2B%285%2F8%29%29=10%2F%282%2A8%29=%282%2A5%29%2F%282%2A8%29=5%2F8
-----The i*sqrt(231) was ommitted because sum of the positive and negative of the expression will be zero.
Axis of Symmetry: highlight%28x=5%2F8%29

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

What is the equation of the axis of symmetry of the graph y=4x^2-5x+16


Axis of symmetry or x-coordinate of vertex = -+b%2F2a



With a being 4, and b being: -+5, axis of symmetry or x-coordinate of vertex is:

-+%28-+5%2F2%284%29%29, or -+%28-+5%2F8%29, or highlight_green%285%2F8%29

You can do the check!! 



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