Question 824770
That input expression looks familiar.  Recognizable or not, just substitute for x in the function and evaluate or simplify as well as possible.


{{{a(-b/(2a))^2+b(-b/(2a))+c}}}
{{{(b^2)/(4a)-(b^2)/(2a)+c}}}
{{{(b^2)/(4a)-2(b^2)/(4a)+4ac/(4a)}}}
{{{(b^2-2b^2+4ac)/(4a)}}}


What would you find if you complete the square on f(x) starting with your general form, and put into Standard Form?  Could that tell you something about -b/(2a)?
Try it!