A bicyclist is riding on a path modeled by the function fx

A bicyclist is riding on a path modeled by the function f(x) = 0.04x, (see figure), where x and f(x) are measured in miles.

Find the rate of change of elevation when x = 2.

Solution

Given f(x) = 0.04x   

we know that rate of change of elevation df(x)/dx

d(0.04x)/dx = 0.04 at all times

when x=2 is also rate of change of elevation = 0.04