On the left the function goes to infinity
on the right it goes to-infinity
Take a look at the horiz. line. It has arrows at both ends. That means that x goes on forever in both directions. Thus, the domain of this function is (-inf, +inf).
Area of wall = 9 * 12 = 108 ft^2
Width of TV = x
Lenght = 2x
Diagonal of TV = 72 " = 6 ft
x^2+(2x)^2=6^2
x^2+4x^2=36
5x^2=35
x^2=36/5
x=sqrt(36/5)
Width = 2.68 ft.
Length = 2.68 * 5.36 = 14.36 ft^2
Area of wall - area of tv = 108 - 14.36 = 93.64 ft
30 im positive is the answer