The total cost faced by a firm in a perfectly competitive is given as:
TC = 600-100Q+0.5Q2
i. Find the profit maximizing level of output of the firm.
ii. Calculate the profit earned at this level.
iii. Is this short-run equilibrium for the firm? Justify your answer.
iv. Should the firm continue to operate in the short-run?
unless you have some formula for revenue, you cannot determine profit.
Now, if you have a constant revenue, then maximum profit is when you have minimum cost. That is just the vertex of the TC parabola, which occurs at
Q = 100