Lynbrook West, an apartment complex, has 100 two-bedroom units. The monthly profit (in dollars) realized from renting out x apartments is given by the following function.

Question

P(x) = -10 x^2 + 1780 x - 54,000
To maximize the monthly rental profit, how many units should be rented out?
units

What is the maximum monthly profit realizable?
$

Answer 1

You know that for the parabola
y = ax^2 + bx + c

the vertex (maximum in this case) is at x = -b/2a

So, plug and chug.