# Math Help - Find the Rate Of change

1. ## Find the Rate Of change

I was given a function here and told to do two things which t is time in hours

$f(x)=20+15e^{kt}$

A.) After 2 hours the persons temperate was 33 C find K

which gave me answer $\frac{ln(\frac{13}{15})}{2}$

B.

Find the rate of change after 4 hours

So what i do is takeout derivative and plug in 4 or solve k for 4 hours and and then take derivative and solve

2. $F(t) = 20 + 15e^{\frac{ln(\frac{13}{15})}{2}*t}$
Find the derivative for the rate of change (F'(x))
then plug in t = 4 hours to find the rate of change at 4 hours.