To find \((f \cdot g)(x)\), we need to multiply the two functions:
\[ f(x) = x \quad \text{(length)} \] \[ g(x) = x + 3 \quad \text{(width)} \]
Now we calculate:
\[ (f \cdot g)(x) = f(x) \cdot g(x) = x \cdot (x + 3) \]
Distributing the \(x\):
\[ x \cdot (x + 3) = x^2 + 3x \]
So, \((f \cdot g)(x) = x^2 + 3x\).
This expression represents the area of the rectangle in square feet, as area is calculated by multiplying the length and width.
Thus, the correct response is:
\((f \cdot g)(x) = x^2 + 3x; \text{ It represents the area of the rectangle in square feet.}\)