Correct question:
A small tie shop finds that at a sales level of x ties per day its marginal profit is MP(x )dollars per tie, where
MP(x) =1.85 + 0.12x - 0.0024x². Also, the shop will lose $65 per day at a sales level of x= 0. Find the profit from operating the shop at a sales level of x ties per day.
Answer:
P(x) =1.85x +0.06x² - 0.0008x³ - 65
Explanation:
Given the marginal profit function:
MP(x) =1.85 +0.12x - 0.0024x², P(0)= -65
We are to find P(x).
P(x) = ∫MP(x) dx
P(x) = ∫(1.85 + 0.12x - 0.0024x²) dx
= ∫1.85 dx+∫0.12x dx+∫(-0.0024x²)dx + C
= 1.85x + 0.06x² - 0.0008x³ + C
Initial condition at P(0) = - 65
where x(0), P(x) = -65
we have:
-65 = 1.85(0)+0.06(0)² - 0.0008x(0)³ + C
-65 = 0 + 0 - 0 + C
-65 = C
C = -65
P(x) =1.85x + 0.06x² - 0.0008x³ - 65