Answer:
12
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 ] = [ 3, 6 ] , then
f(b) = f(6) = 6² + 3(6) + 2 = 36 + 18 + 2 = 56
f(a) = f(3) = 3² + 3(3) + 2 = 9 + 9 + 2 = 20 , then
average rate of change = [tex]\frac{56-20}{6-3}[/tex] = [tex]\frac{36}{3}[/tex] = 12
