The function C(x) = 400x – 0.2x2 represents the total costs for a company to produce a product, where C is the total cost in dollars and x is the number of units sold. Which statement is true?

The coefficient of x² is negative, so the cost function reaches a maximum at its vertex. The vertex occurs at x = −400 ÷ (2 × −0.2) = 1,000, and C(1,000) = 400(1,000) − 0.2(1,000)² = $200,000. Therefore, one thousand units have the maximum cost of $200,000.

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