Consider the following cost curve for a firm in a competitive industry where the market price equals ​$150. C​ = one third q cubed plus 6 q plus 1 comma 500 . What is the​ firm's marginal cost​ (MC)? MC​ = q squared plus 6. ​(Properly format your expression using the tools in the palette. Hover over tools to see keyboard shortcuts.​ E.g., a superscript can be created with the​ ^ character.) At what level of output does the firm maximize profits​ (minimize losses)?