Profit P (x) can be calculated as revenue minus cost. R (x) = 55x - 2x2 C (x) = 21x + 97 P (x) = - 2x2 + 34x - 97 Calculate the x-value that maximizes profit.

8.5

Step-by-step explanation:

The vertex of a quadratic ax²+bx+c is located at x = - b / (2a). When the x² coefficient is negative, the vertex represents a maximum.

For P (x), the x-value of the maximum profit is ...

... x = - 34 / (2 (-2))

... x = 8.5