Answer:
k<±36
Step-by-step explanation:
Δ<0 (no real roots)
b²-4ac<0
k²-4x12x27<0
k²-1296<0
k²<1296
k<±36
Consider a circle with radius
centered at some point
on the
-axis. This circle has equation

Revolve the region bounded by this circle across the
-axis to get a torus. Using the shell method, the volume of the resulting torus is

where
.
So the volume is

Substitute

and the integral becomes

Notice that
is an odd function, so the integral over
is 0. This leaves us with

Write

so the volume is

Since the base is 4x4, and the height is 2, you'll use the 2 as the height of the netting and the 4 as the length. so, it will be 2x4 which is 8ft^2