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# Arithmetic Series $S_n=\frac{n}{2}[2a+(n-1)d]$ or $S_n=\frac{n}{2}(a+t_n)$

- 1Find the sum of the first 40 terms given the arithmetic series:

$$2+5+8+11+...$$ - 2Find the sum of the first 25 terms given the arithmetic series:

$$-3 -7 -11 -15-...$$ - 3Find $S_{30}$ given the arithmetic series:

$$24+19+14+9+...$$ - 4Find the sum given the arithmetic series:

$$3+5+7+9+...+71$$ - 5Find the sum given the arithmetic series:

$$25+18+11+4+...-59$$ - 6Find the sum given the arithmetic series:

$$4+7+10+13+...+127$$ - 7A theatre has 18 seats in the front row and 3 additional seats in each following row.

How many seats are there if the theatre has 20 rows? - 8A log pile has 26 logs on the bottom row. each row above has one less log to form a triangular pile with 1 log at the top.

How many logs are there in the pile? - 9Find the first four terms of the arithmetic series with:

$$t_{12}=35\; \quad S_{20}=610$$

Good test question! - 10Find the first four terms of the arithmetic series with:

$$t_{5}=14\; \quad S_{10}=165$$ - 11The sum of the first four terms of an arithmetic sequence is $50$ and $S_{6}=93$. find the first three terms.$$ $$ Good test question!

$$e=mc^2$$