04
Feb
2019

Week 1 – Precalc 11

categories: Math 11

In the first week of Pre-Calc we learned how to find the sum of an arithmetic series. An arithmetic series is the sum of all the terms in an arithmetic sequence added together. We used the formula S_n = \frac {n} {2} (t_1 + t_n) to find the sum.

In this formula N represents the amount of terms in the sequence. We replace t_1 with the first term in the sequence and t_n with the last term. Once you’ve filled in the variables in the fomula you divide n by 2. Then add the first and last terms together.

Ex. 2, 5, 8, 11, 14….59   t_1=2  t_{20}=59

with this information we can solve for S_n

S_{20} = \frac {20} {2} (2+59)

S_{20}= 10(61)

 

S_{20}=610

 

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