I can't seem to get the right answer for this problem (finding the derivative):
$\displaystyle \overline{c} = \frac{890}{q} + 3600 \cdot \frac{e^{(2q+4)/840}}{q}$
Help would be greatly appreciated.
What is $\displaystyle \overline{c}$? If we assume that it's just functional notation, then:
$\displaystyle \overline{c}' = -\frac{890}{q^2}+3600\cdot \frac{e^{\frac{q+2}{420}} (q-420)}{420 q^2}$ using the chain rule on $\displaystyle e^{\frac{2q+4}{840}$.