Answer
False.
Work Step by Step
General formula for average rate of change from $a$ to $b$: $\dfrac{f(b)-f(a)}{b-a}.$
Hence, here:
$\dfrac{f(b)-f(a)}{b-a}
\\=\dfrac{(2b+8)-(2a+8)}{b-a}
\\=\dfrac{2b+8-2a-8}{b-a}
\\=\dfrac{2b-2a}{b-a}
\\=\dfrac{2(b-a)}{b-a}
\\=2$
Thus, the given statement is false.
