Question

***MEDAL*** What is the common difference of a 43-term arithmetic sequence where the first term is -13 and the sum is 9,374?

Answer 1

well the sum of an arithmetic sequence is

\[S_{n} = \frac{n}{2}[2a + (n - 1) \times d]\]

you know a = -13 and n = 43 and the sum is 9374

just substitute them and solve for d.

Answer 2

thanks!