Asked by kishor
If the 7th term of AP is 21,find the sum of first 13 terms of AP?
Answers
Answered by
Damon
a7 = a + d(6) = 21
{so 2a+12 d = 42}
sum of first 13 = (13/2)(2a + 12d)
= (13/2)(42)
= 13 * 21
= 273
look at:
http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html
{so 2a+12 d = 42}
sum of first 13 = (13/2)(2a + 12d)
= (13/2)(42)
= 13 * 21
= 273
look at:
http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html
There are no AI answers yet. The ability to request AI answers is coming soon!
Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.