The ordering and transportation cost C (in thousands of dollars) for machine parts is given by C

Question:

The ordering and transportation cost C (in thousands of dollars) for machine parts is given by
C (x) = 100(200/x2 + x/x + 30), x ≤ 1
where x is the order size (in hundreds). In calculus, it can be shown that the cost is a minimum when
3x3 − 40x2 − 2400x − 36,000 = 0
Use a graphing utility to approximate the optimal order size to the nearest hundred units.