Answer:
the change in C can be calculated by evaluating the cost function at Q = 356 and Q = 357
change in C = 1,020,000/357 + 7.6*357 - 1,020,000/356 + 7.6*356 ≈ -0.43
Instantaneous rate of change in C is first order derivative C':
C'(Q) = -1,020,000/(Q^2) + 7.6
C'(356) = -1,020,000/(356^2) + 7.6 ≈ - 0.45
Hope my answer helps.
