Answer: The correct option is (A) (2x + 7) feet.
Step-by-step explanation: Given that Rhett decides to build a square room for his movie and music collection and the area of the room is (4x2 + 28x + 49) square feet.
We are to find the length of one side of the room.
We know that the area of a square having side length of 'a' units is a² square units.
So, to find the side length of the square room, we need to convert the area in form of a perfect square.
The are of the square room is
[tex]A=4x^2+28x+49=(2x)^2+2\times 2x\times 7+7^2=(2x+7)^2~\textup{sq. feet}.[/tex]
Since the area of the square room is (2x + 7)², so the length of one side of the room will be (2x + 7) feet.
