
William W. answered 08/03/22
Experienced Tutor and Retired Engineer
Profit (P) equals Revenue (R) minus Cost (C):
P(x) = R(x) - C(x)
P(x) = (2500 - 5x2) - (40 + 3x)
P(x) = 2500 - 5x2 - 40 - 3x
P(x) = -5x2 - 3x + 2460
This is an upside-down parabola so it will have a maximum (which you are looking for). To find the maximum, take the derivative and set it equal to zero:
P'(x) = -10x - 3
Setting this equal to zero: -10x - 3 = 0 means x = -3/10
In this case, the maximum profit occurs when the company makes negative units. That's really strange. The more units the company makes, the less profit they make. Since they can't actually make negative units, then they should make zero units for which their profit is $2460.
Perhaps you made an error in transcribing the problem. If not, I suggest the company develop new models because to make nothing and still produce a profit sounds suspect.