Question

find the sum of first 12 odd numbers.

with formula please ​

Answer 1

Answer:

First term of the given arithmetic series = 1

Second term of the given arithmetic series = 3

Third term of the given arithmetic series = 5

Fourth term of the given arithmetic series = 7

Now, Second term - First term = 3 - 1 = 2

Third term - Second term = 5 - 3 = 2

Therefore, common difference of the given arithmetic series is 2.

The number of terms of the given A. P. series (n) = 12

We know that the sum of first n terms of the Arithmetic Progress, whose first term = a and common difference = d is

S

n

=

2

n

[2a+(n−1)d]

S

12

=

2

12

[2×1+(12−1)2]

S

12

=6[2+22]