Question

Try to draw the geometrical figures for other identities.

(x + a) (x + b) ≡ x² + (a + b) x + ab

Answer 1

Step – 1 : Area of fig. I = x² 

Step – 2 : Area of fig. II = ax 

Step – 3 : Area of fig. Ill = bx 

Step – 4 : Area of fig. IV = ab 

∴ Area of big rectangle = Sum of areas of four small figures. 

∴ (x + a) (x + b) = x² + ax + bx + ab 

(x + a) (x + b) = x² + (a + b) x + ab