What is the sum of the arithmetic sequence 9, 14, 19, …, if there are 38 terms?

1 Answer
Jan 14, 2016

3857

Explanation:

The sum of an arithmetic sequence where x_n = a +(n-1)d
is given by sum_(n=0)^(n=38) = n/2(2a+(n-1)d)

In this example a=9 and d=5 as the first term is9 and the difference between each term is 5. There are 38 terms

So sum_(n=0)^(n=38) =38/2(2*9 + 37*5) =19(18+185)=19*203

=3857