Answer:
8
Step-by-step explanation:
The average rate of change is measured as
[tex]\frac{f(b)-f(a)}{b-a}[/tex] in the closed interval [ a, b ]
here [a, b ] = [ - 3, 8 ]
f(b) = f(8) = 8² + 3(8) - 4 = 64 + 24 - 4 = 84
f(a) = f(- 3) = (- 3)² + 3(- 3) - 4 = 9 - 9 - 4 = - 4
average rate of change = [tex]\frac{84-(-4)}{8-(-3)}[/tex] = [tex]\frac{88}{11}[/tex] = 8
