Answer
$1$
Work Step by Step
Integrate the integral to calculate the volume as follows:
We have: $V= \pi \times \int_{a}^{b} f^2(x) dx =6 \pi$
or, $ \int_{a}^{b} (f(x)+2)^2- 4 dx=10 \pi$
or, $ \int_{a}^{b} (f(x)+2)^2-4 dx=10$
or, $6+ (4) \int_{a}^{b} f(x) dx=10$
Thus, our answer is: $\int_{a}^{b} f(x) dx= 1$