Question

The daily production costs C (in dollars per unit) for a manufacturer of lighting fixtures are given by the quadratic function C(X)=800-10X+0.25X2 where x is the number of units produced. How many fixtures should be produced to yield a minimum cost per unit?

Answer 1

the minimum cost is found at the vertex of the parabola. As you recall, that is at x = -b/2a, or in this case

x = 10/.5 = 20