To calculate \((f \cdot g)(x)\), we will multiply the functions \(f(x)\) and \(g(x)\):
Given:
- \(f(x) = x\)
- \(g(x) = x + 3\)
Now let's compute \((f \cdot g)(x)\): \[ (f \cdot g)(x) = f(x) \cdot g(x) = x \cdot (x + 3) \] \[ = x^2 + 3x \]
This result, \(x^2 + 3x\), represents the area of the rectangle in square feet, where \(f(x)\) is the length and \(g(x)\) is the width.
So the correct response is: \[ (f \cdot g)(x) = x^2 + 3x; \text{ It represents the area of the rectangle in square feet.} \]