Viva Voce Sum of Odd Natural Numbers - Class 10 PDF Download

Q.1. Give the formula for sum of first (« + 1) natural numbers.

S_n+1 =(n+2)(n+1)/2

Q.2. What is the sum of 2 + 6 + 10 + 14 + 18 + … + 10 terms?

200
[Hint: 2 [1 + 3 + 5 +… + 10 terms] =2 x 10²= 200]

Q.3. What is the n th term of 2 + 4 + 6?

a_n = 2n

Q.4. Define odd numbers and which is the first odd natural number.

Numbers which are not divisible by 2 are known as odd numbers. 1 is the first odd natural number.

Q.5.What is the sum of first n natural numbers?

S_n = n(n+1) /2

Q.6. What is the sum of first n multiples of 5?

5 × n(n+1) /2

Q.7. What is the #th term of  1 + 3 + 5?

a_n =(2n— 1)

Q.8. Give the formula for the sum to n terms of an AP.

S_n= n / 2 [2a+(n−a)d]

Q.9. If  n th term of an AP is (2n + 1), find the sum of first n terms of the AP.

n(n+ 2)

Q.10. First term of an AP is p and its common difference is q then its 10th term is

p + 9q