If the side of the square is increased by 10%, then its area will increase by 84 dm2.

If the side of the square is increased by 10%, then its area will increase by 84 dm2. Calculate the side of the square and its area before enlarging.

Let the side of the square be equal to X dm, then after increasing it by 10%, its length will be 1.1 * X dm.

The area of the original square is X ^ 2, and the new square is 1.21 * X ^ 2.

The area difference is equal to: (1.21 * X ^ 2 – X ^ 2) = 84 dm2.

0.21 * X ^ 2 = 84.

X ^ 2 = 400.

X = 20 cm.

Sq = 20 ^ 2 = 400 dm2.

Answer: The side of the square is 20 cm, the area is 400 dm2.