To find the area of the square rug, you simply square the length of one of its sides.
Given that the side of the square rug is \(5x + 1\) feet, the area \(A\) is calculated as:
\[ A = (5x + 1)^2 \]
Expanding the equation gives:
\[ A = 25x^2 + 10x + 1 \]
So, the area of the square rug is (25x^2 + 10x + 1)square feet.