Answer:
10
Step-by-step explanation:
The average rate of change of f(x) in the closed interval [ a, b ] is
[tex]\frac{f(b)-f(a)}{b-a}[/tex]
here [ a, b ] = [1, 4 ]
f(b) = f(4) = 4² +5(4) = 16 + 20 = 36
f(a) = f(1) = 1² + 5(1) = 1 + 5 = 6, hence
average rate of change = [tex]\frac{36-6}{4-1}[/tex] = [tex]\frac{30}{3}[/tex] = 10
