Question 853683
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(x=(5+- i*sqrt(231))/8)}}}, the zeros or roots.
The exact middle is the AVERAGE of those.
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{{{(1/2)((5/8)+(5/8))=10/(2*8)=(2*5)/(2*8)=5/8}}}
-----The i*sqrt(231) was ommitted because sum of the positive and negative of the expression will be zero.
Axis of Symmetry: {{{highlight(x=5/8)}}}