Question

The sum of all odd number from 1 to32

Answer 1

1,3,5...31
D = 3-1=2
An = A + ( n-1) d
31 = 1 + (n - 1 ) 2
31 -1 = ( n - 1 ) 2
30/2 = ( n - 1 )
15 + 1 = n
n =16
Sn = n /2+( a + An)
= 16/2 + ( 1 + 31)
= 8 + 32
= 40