A manufactureer determines that the number of drills it can sell is given by the formula D= -3p^2 + 174p - 310 where p is the price of the drills in dollars
D= -3p2 + 174p - 310
Let's take the derivative and set it equal to zero.
The answer is $29.
This is the vertex of the downward parabola. We know it is downward because 3p2 is negative. The vertex is the point at which rate of change is zero.