Determine the number of terms in the following arithmetic sequence 315,304,293,..... ,18.
1 answer
The common difference between terms in an arithmetic sequence is obtained by subtracting any term from its subsequent term. So, we obtain $315-304=304-293=\cdots=33-18=15$. Listing every term in this sequence would be tedious, so we note that $315=18+15(19)$: the common difference has been applied 19 times, so there are $\boxed{20}$ terms.
1 answer