# Thread: Volumes and average value

1. ## Volumes and average value

I am studying for a test tomorrow and need help on two questions. Thanks!

1. Find the volume generated by revolving the region about the x-axis:
y= -3x-x^2 and y=0

2. Find the average value of the function:
y=square root of: 2x+1 on the interval [4,12]

2. Originally Posted by cam_ddrt
I am studying for a test tomorrow and need help on two questions. Thanks!

1. Find the volume generated by revolving the region about the x-axis:
y= -3x-x^2 and y=0

2. Find the average value of the function:
y=square root of: 2x+1 on the interval [4,12]
1. $V = \pi \int_{-3}^0 (-3x-x^2)^2 \, dx$

2. $\frac{1}{12-4} \int_4^{12} \sqrt{2x+1} \, dx$