Asked by Utibe
The fourth and ninth term of an a.p are -3 and 12 repectively find:the common different and the sum of the first seven term.
Answers
Answered by
Reiny
a+3d = -3
a+8d = 12
subtract:
5d = 15
d = 15/5 = 3
a + 9 = -3
a = -12
common difference is 3
sum(7) = (7/2)(-24 + 6(3)) = -21
a+8d = 12
subtract:
5d = 15
d = 15/5 = 3
a + 9 = -3
a = -12
common difference is 3
sum(7) = (7/2)(-24 + 6(3)) = -21
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.