Question

1+3+5+7+.........+23=?

Answer 1

This question is from AP

a = 1

d = 3 - 1 = 2

tn = 23

Tn = a + (n - 1 ) d

23 = 1 + ( n - 1 ) 2

23 = 1 + 2n - 2

24 = 2n

n = 12

Since, we know that the sum of Ap formula

sm = n/2 ( a + l)

sm = 12/2 ( 1 + 24)

sm = 6 × 25

sm = 150 Answer ✔