Side of the original square is 5 cm.
Explanation:
- Step 1: Let the side of the original square be x. Then side of the new square = x + 3 and Area of new square = 64 cm²
Area of a square = (side)²
⇒ 64 = (x + 3)²
⇒ 64 = x² + 6x + 9
⇒ x² + 6x - 55 = 0
⇒ x² + 11x - 5x - 55 = 0 (Since 6x = 11x - 5x as part of factorizing)
⇒ x(x + 11) - 5(x + 11) = 0
⇒ (x + 11)(x - 5) = 0
⇒ x = -11 and x = 5 (Lengths can't be negative)
Side of the original square is 5 cm.