Question

submittion of 19 odd numbers​

Answer 1

Answer:

n (n+1)/6= 19(19+1)/6

Answer 2

Answer:

Step-by-step explanation:

Firstly..... It's not submittion, it's summation.

It's means summing up or adding all the given nos.

Here, the summation of 19 odd nos. is asked.

It means

1 +3+5+7+9+.............( upto 19th odd number)

We know that every even no. Is of the form 2n where n =1,2,3.....

Every odd number is even number +1 (think over it)

Therefore every odd number is of the form (2n +1)

19th odd no. =2n +1 where n =19

=2multiplied by 19, +1

=38+1=39

Now you know the last term of summation

Use AP formula Sn equals n/2[2a +(n-1)d]

n =19, a=1 ,d=2