Assume that​ C(x) is in dollars and x is the number of units produced and sold. For the​ total-cost function ​C(x) equals 0.01x² + 0.6x + 40​, find ΔC and C'(x) when x equals 60 and Δx equals 1.
a) ΔC = 61.61, C'(x) = 0.7
b) ΔC = 62.21, C'(x) = 0.6
c) ΔC = 61.2, C'(x) = 0.61
d) ΔC = 62.81, C'(x) = 0.59