Answer:
Yes, the area of the square would be a rational number.
Explanation:
Area of square = 400 units² = x²
x = one side length of square
x = √400 = 20 units
Increase each side length by 1 unit.
New side length = 21 units
Area of new square = 21² = 441
441 is a rational number because the square root of 400 is a rational number.
√400 = 21
Therefore: If the length of each side of the square increased by one unit, the area of the square would be a rational number. The area of the square would still be a perfect square.