Page 27 - Mathematics Class - IX

ACTIVITY 2.4

OBJECTIVE

To verify the algebraic identity: a + b = (a + b)(a – ab + b )
3
3
2
2
MATERIALS REQUIRED
Cubes of dimensions (1 × 1 × 1) cm. (Around 60 in number) in different colours

Glazed paper of different colours

PRE-REQUISITE KNOWLEDGE
1. Concept of volume of cube = (edge) 3 2. Concept of volume of cuboid = l × b × h

THEORY
For the concepts of cube and cuboid refer to Activity 2.2.

PROCEDURE

1. Let’s take the value of ‘a’ as 3 units and ‘b’ as 1 units. Arrange the unit cubes to make a larger cube of
(3 × 3 × 3) using 27 cubes of red colour as shown in Fig. (a).

a = 3

a = 3

a = 3
Fig. (a)

2. Take one cube of yellow colour as b = 1 unit as shown in Fig. (b)

b = 1

b = 1
b = 1
Fig. (b)

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