Answer:
260 units
Step-by-step explanation:
C(qi) = 160 = 58(qi) - 6(qi)² + (qi)³
dC/d(qi) = 58 - 12(qi) + 3(qi)²
d²C/d(qi)² = 6qi - 12
For d²C/d(qi)² = 0
Hence, 6qi - 12 = 0
6(qi - 2) = 0
∴ qi = 2
When, qi = 2: C(qi) = 160 + 116 - 24 + 8 = 260 units