An arithmetic series has a common difference of 7. Given that the sum of the first 20 terms of the series is 530, Please, help me with finding the first term of the series

cochetezgh

cochetezgh

Answered question

2022-09-05

An arithmetic series has a common difference of 7. Given that the sum of the first 20 terms of the series is 530, Please, help me with finding the first term of the series

Answer & Explanation

zagrebova1c

zagrebova1c

Beginner2022-09-06Added 10 answers

With the first term as a and common difference d, the sum for n terms = n a + n ( n - 1 ) 2 d , using 1 + 2 + 3 +..(n-1) = (n-1)(n)/2
Here, n = 20 and d = 7.
20a + ((19)(20)/2)7 = 530
20a=−100. So, a = −5.

Do you have a similar question?

Recalculate according to your conditions!

Ask your question.
Get an expert answer.

Let our experts help you. Answer in as fast as 15 minutes.

Didn't find what you were looking for?