Differentiate a thermo equation

1. Oct 17, 2011

juggalomike

1. The problem statement, all variables and given/known data
Air at 300K(=T_s) flows over a flat plate maintained at 400K(=T_f). At a particular location on the plate, the temperature distribution in the air measure from the plate surface is given by
T(y)=(T_s-T_f)exp[-22,000*y(m)]+T_f

Q.Determine the conduction heat flux through the air at the plate surface where the no-slip condition applies.

2. Relevant equations
flux=-k*dT(y)/dy

3. The attempt at a solution
The value of k can be looked up from a table in my book, my instinct is the differentiate the t(y) equation but i am lost when it comes to taking its derivative. Which makes me wonder if we actually need the derivative or there is an easier approach. Any help is appreciated, thanks.