Answer:
a)
degrees
b) 
Step-by-step explanation:
An approximate formula for the heat index that is valid for (T ,H) near (90, 40) is:

a) Calculate I at (T ,H) = (95, 50).
degrees
(b) Which partial derivative tells us the increase in I per degree increase in T when (T ,H) = (95, 50)? Calculate this partial derivative.
This is the partial derivative of I in function of T, that is
. So



The domain of this equation is the lowest x value to the highest x value. For example: lowest is -4 and highest is 3. You would write it as [-4,3]
For this equation, the domain is (-infinity,infinity) because there is no lowest or highest x value.