according to the definition of the average rate of change over an interval [a,b] is defined as
[tex]\frac{f(b)-f(a)}{b-a}[/tex]
define the points over the interval (0,4)
(0,1) & (4,5)
replace in the formula
[tex]\frac{5-1}{4-0}=\frac{4}{4}=1[/tex]
the average rate of change is 1.
