this is applied maximum and minimum problems

(a) a chemical manufacturer sells sulfuric acid in bulk at a price of $100 per unit. If the daily total production cost in dollars for x units is

C(x)=100,000+50x+0.0025x^2

and if the daily production capacity is at most 7000 units, how many units of sulfuric acid must be manufactured and sold daily to maximize the profit?

(b) would it benefit the manufacturer to expand the daily productin capacity?

(c) use marginal analysis to approximate the effect on profit if daily production could be increased from 7000 to 7001 units.