Answer:
To have maximum profit, the price must be increased by 5,
Step-by-step explanation:
Given that the price increase function is:
f(x) = -2x² + 20x + 150,
For maximum profit, then f(x) = 0.
Putting f(x) = 0, we have
-2x² + 20x + 150 = 0
Or
x² - 10x - 75 = 0
(x + 5)(x - 15) = 0
x = -5
Or
x = 15
Again, differentiating f(x) and equating to zero, we have
-4x + 20 = 0
4x = 20
x = 20/4
= 5
To have maximum profit, the price must be increased by 5,