for the function f(x)=5/x+4, find the average rate of change of f from 1 to x.
please show work
you need (f(x)-f(1))/(x-1)
= (5/(x+4) - 5/(1+4))/(x-1)
= (5/(x+4) - 1)/(x-1)
= ((5-(x+4))/(x+4))/(x-1)
= (1-x)/((x+4)(x-1))
= -1/(x+4)
makes sense, since f is decreasing on x>1