First sketch square ABCD. Split length into 3cm and then xcm for side AB and the same for side AD. Split the area of this square into 4 segments (a, b, c and d) such that a is a 3cm by 3cm square, b and c are 3cm by xcm rectangle s and d is a xcm by xcm square.Area of a, b, c and d sum to 10cm^2.Area of a : 3 x 3 = 9 Area of b : 3 x 'x' = 3xArea of c : 3 x 'x' = 3xArea of d : 'x' x 'x' = x^2x^2 + 6x + 9 = 10x^2 + 6x = 1