Answer:
3
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, 2 ]
f(b) = f(2) = 2² - 3 = 4 - 3 = 1
f(a) = f(1) = 1² - 3 = 1 - 3 = - 2, thus
average rate of change = [tex]\frac{1-(-2)}{2-1}[/tex] = 3
