 ## Book: NCERT - Mathematics

### Chapter: 9. Algebraic Expressions and Identities

#### Subject: Maths - Class 8th

##### Q. No. 6 of Exercises 9.5

Listen NCERT Audio Books - Kitabein Ab Bolengi

6
##### Using identities, evaluate.(i) (ii) (iii) (iv) (v) (vi) (vii) (viii) (ix) (i) We can write 70 as 70 + 1

Using Identity (a + b) 2 = a2 + 2ab + b2 for finding the value of In the given expression a = On substituting these values in the above identity, we get  (ii) We can write 100 as 100 - 1

Using Identity (a - b) 2 = a2 - 2ab + b2 for finding the value of In the given expression a = On substituting these values in the above identity, we get  (iii) We can write 102 as 100 + 2

Using Identity (a + b) 2 = a2 + 2ab + b2 for finding the value of In the given expression a = On substituting these values in the above identity, we get  (iv) We can write 998 as 1000 - 2

Using Identity (a - b) 2 = a2 - 2ab + b2 for finding the value of In the given expression a = On substituting these values in the above identity, we get  (v) We can write 5.2 as 5 + 0.2

Using Identity (a + b) 2 = a2 + 2ab + b2 for finding the value of In the given expression a = On substituting these values in the above identity, we get  (vi) 297× 303

We can write 297 as 300 – 3 and 303 as 300 + 3

Using Identity  In the given expression On substituting these values in the above identity, we get = (vii) 78 × 82

We can write 78 as 80 – 2 and 82 as 80 + 2

Using Identity  In the given expression On substituting these values in the above identity, we get = (viii) We can write 8.9 as 8 + 0.9

Using Identity (a + b) 2 = a2 + 2ab + b2 for finding the value of In the given expression a = On substituting these values in the above identity, we get  (ix) 1.05 × 9.5 = 1.05 × 0.95 × 10

We can write 1.05 as 1 + 0.05 and 0.95 × 10 as (1 – 0.05) × 10

Using Identity   6

1
2
1
4
5
6
7
8