Question

The function f(x) = –(x – 20)(x – 100) represents a company’s monthly profit as a function of x, the number of purchase orders received. Which number of purchase orders will generate the greatest profit?

20
60
80
100

Answer 1

Answer: 60

Explanation:

Essentially, they are asking for the highest point in the graph, which means that the graph opens down and most likely all the points with x=positive are in quadrant 1.

So we need to find the axis of symmetry, which can be calculated as ((x-intercept 1)-(x-intercept 2))/2

Since it says (x-20) and (x-100), the intercepts are clearly 20 and 100.

(20+100)/2=60

Don't worry about the negative before the (x-20), it just means that the graph opens downward.