posted by Andrea .
I'm having some troubles with these. Thanks in advance.
If a>0 find the minimum value. If a<0 find the maximum value.
These are functions for parabolas, so
f(x)=ax²+bx+c when a does not equal 0
In both your examples, the "a", which is the coefficient of the x^2 term, is negative.
1. dy/dx = -2x + 2, and that equals zero at a maximum or minimum. So the maximum would occur at x=1.
d2y/dx^2 = -2. Since that is always negative, x=1 is a point of maximum value.
Do #2 similarly.
Thank-you, but I really don't understand what you mean by dy/dx. I'm feeling terribly stupid, but nothing like that is in my book.
Find Minimum or maximum value of f(x)=2x^2 + 3x -9