The domain is all the numbers of which the inputs can be put. Here, we have a graph, which simplifies things. We just need to look at the x-values of the graph, or the horizontal line. The graph extends both negatively and positively. Thus since the graph extends both ways (right and left) forever, the answer would be D, or all real numbers.
Your answer would be 51.6
Solution :
Given :
Span of the roof = 48 feet
Length of the rafter = 30 feet (including the 4 feet overhung)
So, for the 30 feet long rafter, 26 feet will be rafter length from the high point of the roof to the edge of the roof and 4 feet will be the roof overhung.
Therefore, the horizontal span per rafter is

= 24 feet
a). So the rise of the roof is
= 10 feet
b). Pinch of the roof is 


c). The percent of the roof used as overhung is


= 13.33 %
Sqrt[x] = -x
x= x ^ 2
x - x^2 = 0
-x(x-1)=0
x(x-1)=0
x = 1 or x = 0
sqrt 1 isn not equal to 0
x= 0