Question

A chess board contains 64 equal squares and the area of each square is 6.25 cm². A border round the board is 2 cm wide find its side.

Answer 1

Let the length of the side of the chess board be x cm. Then,

Area of 64 squares = (x – 4)²

(x – 4)² = 64 x 6.25

⇒ x² – 8x + 16 = 400

⇒ x² – 8x - 384 = 0

⇒ x² – 24x + 16x – 384 = 0

⇒ (x – 24)(x + 16) = 0

⇒ x = 24 cm