In an A.P sum of the first 2 term is 5 and sum of the last 2 term is 129. Then find the sequence
Asked by dhruthanmn | 6th Jun, 2020, 03:35: PM
According to the question,
a + (a+d) = 5
2a + d = 5 .... (i)
2a + d(2n-3) = 129 ... (ii)
Subtracting (i) from (ii), we get
d(2n-4) = 124
d(n-2) = 62
n = 62/d + 2
Since n has to be a non-zero positive integer.
Therefore, d can take the values 1, 2, 31 or 62
Basis on this, find the value of a and hence the sequence.
Answered by Renu Varma | 6th Jun, 2020, 09:07: PM
- sn denotes the sum of first n terms of an AP, whose common difference is d, then Sn-2Sn-1 + Sn-2 (n > 2) is equal to A) 2d B) -d C) d D) None of these Explain solution please
- Sir/Madam Plss solve it Sum of all integers between 100 and 500 which are divisible by 17
- Plz solve this question
- Sum of first m terms of an A.P. is 0. If a be the first term of the A.P., then the sum of next n terms is : (A) 1 ( ) − − + m a m n m (B) 1 ( ) − − + m a m n n (C) 1 ( ) − − + n a m n n (D) 1 ( ) − − + n a m n m
- Question 1) Find the sum of first 40 positive integers divisible by 6. Question 2) Find the sum of n terms of the series (4-1/n)+4-2/n)+(4-3/n)+........ Question 3) If the sum of the first n terms of an AP is 1/2(3n²+7n), then find its nth term .Hence write the 20 th term .
- A3=15,S10=125,find d and a10
- Find the sum of the first 17 term of an AP whose 4th term = -15 and 9th term = -30.
- The sum of n term of an ap is 4n^2-3n.find 20th term of this ap
Kindly Sign up for a personalised experience
- Ask Study Doubts
- Sample Papers
- Past Year Papers
- Textbook Solutions
Verify mobile number
Enter the OTP sent to your number