![S_n=\frac{n}{2}[2a+(n-1)d]](/tpl/images/0428/4943/b603c.png)
![S_{21}=\frac{21}{2}[2(-5)+(21-1)(2)]](/tpl/images/0428/4943/b8082.png)
![S_{21}=\frac{21}{2}[-10+40]](/tpl/images/0428/4943/b73b6.png)
What is the sum of the first 21 terms of this arithmetic series?
-5+(-3)+(-1)+1+...
Mathematics, 21.12.2019 01:31 jfrjtwrg
What is the sum of the first 21 terms of this arithmetic series?
-5+(-3)+(-1)+1+
Answers: 2
Another question on Mathematics
Mathematics, 21.06.2019 20:30
Solve each quadratic equation by factoring and using the zero product property. n^2 - 49 = 0
Answers: 2
Mathematics, 22.06.2019 00:30
1. according to the internal revenue service, the mean tax refund for the year 2007 was $2,708. assume the standard deviation is $650 and that the amounts refunded follow a normal probability distribution. a. what percent of the refunds are more than $3,000? b. what percent of the refunds are more than $3,000 but less than $4,000? c. what percent of the refunds are less than $2,000?
Answers: 2
Mathematics, 22.06.2019 05:30
If m is the midpoint of ln and ln=27.8 find the length of mn
Answers: 2
You know the right answer?
Questions
Mathematics, 02.10.2020 15:01
Social Studies, 02.10.2020 15:01
Mathematics, 02.10.2020 15:01
Mathematics, 02.10.2020 15:01
Social Studies, 02.10.2020 15:01
English, 02.10.2020 15:01
History, 02.10.2020 15:01
Mathematics, 02.10.2020 15:01
English, 02.10.2020 15:01
Mathematics, 02.10.2020 15:01
Mathematics, 02.10.2020 15:01
Mathematics, 02.10.2020 15:01
Mathematics, 02.10.2020 15:01
