Answer: The length of the original side of the square is 22 units.
Explanation:
Let x be the length of the original side of the square.
If the sides are increased by 11, the new side length is x + 11.
The area of the new square is given as 400, so we have:
(x + 11)^2 = 400
Expanding the left side: x^2 + 22x + 121 = 400
Subtracting 400 from both sides: x^2 + 22x - 279 = 0
Using the quadratic formula:
x = (-22 ± sqrt(22^2 - 41(-279))) / (2*1)
x = (-22 ± sqrt(12100)) / 2
x = (-22 ± 110) / 2
Taking the positive solution:
x = (-22 + 110) / 2
x = 44 / 2
x = 22