Question

Find the sum of the first 18 odd positive integers.

Answer 1

The sum of the first 18 odd positive integers is 324.

Explanation:

Given : The first 18 odd positive integers.

To find : The sum of the first 18 odd positive integers?

Solution :

The odd positive integers are 1,3,5,.... forming an Arithmetic sequence .

Where, First term is a=1

Common difference is d=2

Number of terms n=18

The sum of A.P formula is

`S_n=(n)/(2)[2a+(n-1)d]`

Substitute the values in the formula,

`S_(18)=(18)/(2)[2(1)+(18-1)2]`

`S_(18)=9[2+(17)2]`

`S_(18)=9[2+34]`

`S_(18)=9[36]`

`S_(18)=324`

Therefore, The sum of the first 18 odd positive integers is 324.