1. Differentiate the utility function:
U(q) = -2q^2 + 40q + 12,580
U'(q) = \frac{d}{dq}(-2q^2 + 40q + 12,580) = -4q + 40
2. Set the derivative equal to zero to find the critical points:
-4q + 40 = 0
-4q = -40
q = 10
3. Use the second derivative to confirm it's a maximum:
U''(q) = \frac{d}{dq}(-4q + 40) = -4
Since U''(q) = -4 is negative, this confirms a maximum at q = 10.
Answer: The number of units that maximizes utility is q = 10 .