Question

Without doing the actual addition, find the sum of: (i) 1 + 3 + 5 + 7 + 9

Answer 1

Here a = 1 ,
d = 2 ,
n = 5 ,
last term = 9

We know that ,

Sn = n /2 ( a + l )

= 5/2 ( 1+9)

= 5/2 * 10

= 5 * 5

= 25

Thus the sum is 25

Answer 2

HIII.....


HERE IS YOUR ANSWER:--------


HERE A IS 1
d= 2,n=5 AND last term=9

A/Q,

5/2=(1+9)
5/2*10=25.


HOPE THIS HELPS YOU.....