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![Use this identity to find the square of a number, say 119 [Class 9] - More Identities](https://cdn.teachoo.com/69e84134-e4bb-4f7f-ba31-ff34ce25bb09/slide63.jpg)
Example 9 - Chapter 4 Class 9 - Exploring Algebraic Identities (Ganita Manjari I)
Last updated at May 15, 2026 by Teachoo
Class 9
Chapter 4 Class 9 - Exploring Algebraic Identities (Ganita Manjari I)
- Consecutive Square Numbers
- Visualising Algebraic Identities
- Exercise Set 4.1
- Factorisation of Algebraic Expressions Using Identities
- Exercise Set 4.2
-
More Identities
- Exercise Set 4.3
- Rewriting a2 - b2 Identity
- Factorisation Using Algebra Tiles
- Factorisation by Splitting the Middle term
- Exercise Set 4.4
- Finding New Algebraic Identities
- Simplifying Rational Expressions
- Exercise Set 4.5
- Word Problems
- End-of-Chapter Exercises
Transcript
Example 9 Use this identity to find the square of a number, say 119 We have to use the identity (𝒂+𝒃+𝒄)^𝟐=𝒂^𝟐+𝒃^𝟐+𝒄^𝟐+𝟐𝒂𝒃+𝟐𝒃𝒄+𝟐𝒂𝒄 We write 119 as a sum of 3 numbers whose square is easy to find So, we can write 119 = 100 + 10 + 9 Now, finding square 〖𝟏𝟏𝟗〗^𝟐=(𝟏𝟎𝟎+𝟏𝟎+𝟗)^𝟐 Using (𝑎+𝑏+𝑐)^2=𝑎^2+𝑏^2+𝑐^2+2𝑎𝑏+2𝑏𝑐+2𝑎𝑐 Putting 𝑎 = 100, 𝑏 = 10 & 𝑐 = 9 =100^2+10^2+9^2+2 × 100 × 10+2 × 100 × 9+2 × 10 × 9 =10,000+100+81+2,000+1,800+180 =10,000+100+81+2,000+1,800+180 =𝟏𝟒,𝟏𝟔𝟏
