Find the absolute maximum and the absolute minimum value, if any of:
f(x)= (-1x^2/8)+4x+3 on the interval (0,9)
In the usual syntax,
-1/8 x^2 + 4x + 3
You should recognize that as a parabola which opens downward. Its vertex is at x = 16, which is to the right of our interval. So, the min will be at x=0 and the max will be at x=9.
Incidentally, your interval should be [0,9], not (0,9).
See the graph at
http://www.wolframalpha.com/input/?i=-1%2F8+x^2+%2B+4x+%2B+3