Q8 of 202 Page 10

Write the sum of first n odd natural numbers.

First n odd numbers are 1, 3, 5, 7, 9........., (2n–1) which forms an A.P

a= 1

l= 2n – 1 where l be the last term

S_n = (2a + (n–1) d) or (a + l)

= (1 + 2n –1)

= (2n)

=n (n)

=n²

Write the value of x for which 2x, x + 10 and 3x + 2 are in A.P.

Write the nth term of an A.P. the sum of whose n terms is S_n.

Write the sum of first n even natural numbers.

1f the sum of n terms of an A.P. is S_n = 3n² + 5n. Write its common difference.