Question

The volume of a certain cylinder, V, varies directly as the SQUARE of the radius, r. If V = 16π when the r = 2, then the equation for the volume, V is

V=4 π r2
V = 2 π r2
V = 16 π r2
V=4π over r^2

Answer 1

V varies directly as the square of r so
\[V = kr^2\]
when v = 16 pi, r = 2 so
\[16 \pi = k(2^2)\]
\[16 \pi = 4k\]
\[\frac{16\pi}{4} = k\]
\[4\pi = k\]
does that help?

Answer 2

so is it the fist one

Answer 3

yup