SOLUTION: The first term of an Ap is-1 and the sum of the first twenty terms is -240 .find the third term

Question 1134277: The first term of an Ap is-1 and the sum of the first twenty terms is -240 .find the third term
Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!

The sum of the first 20 terms of an AP is 20 times the average of the first and 20th terms. So if x is the 20th term,

The first term is -1; the 20th term -- the first term plus the common difference 19 times -- is -23. So the common difference is

(not a very pleasant sequence....)

The third term is the first term plus the common difference twice:

or -3 6/19
RELATED QUESTIONS
The sixth term of an AP is 37 an the tenth term 53.Find the sum of the first twenty... (answered by KMST)

The term of an AP is 37 and the tenth term 53.Find sum of the twenty... (answered by ewatrrr)

The twenty first term of an ap is five and a half while the sum of the twenty one terms... (answered by greenestamps)

The first term of an AP is 7 and the sum of the first 40 terms is 1216. find the nth... (answered by ikleyn,josgarithmetic,Theo)

The first, second and third term of a GP are the first, third and seventh term of an AP... (answered by greenestamps)

Find the sum of the first 25 terms of an AP whose nth term is... (answered by stanbon)

Find the sum of first 15 terms of an AP., whose nth term is... (answered by mananth)

The twenty first term of an app is five and a half while the sum of the twenty one terms... (answered by Theo)

the 6th term of an ap is 29 and 13th term is 64. calculate the first term common... (answered by Fombitz)