The area of a square is calculated using the formula:
\[ \text{Area} = \text{side}^2 \]
Given that the length of the side of the square is \(5x + 2\), we can substitute this into the formula:
\[ \text{Area} = (5x + 2)^2 \]
Now, we will expand this expression:
\[ (5x + 2)^2 = (5x)^2 + 2(5x)(2) + (2)^2 \]
Calculating each term step by step:
\[ (5x)^2 = 25x^2 \] \[ 2(5x)(2) = 20x \] \[ (2)^2 = 4 \]
Now, we can combine these results:
\[ \text{Area} = 25x^2 + 20x + 4 \]
Therefore, the area of the square in standard form is:
\[ \boxed{25x^2+20x+4} \]