Advertisements
Advertisements
प्रश्न
Which term of the AP 21, 18, 15, …… is -81?
Advertisements
उत्तर
The given AP is 21,18,15,.......
First term, a = 21
Common difference, d= 18 -21 =-3
Suppose nth term of the given AP is - 81. then,
an = -81
⇒ 21 +(n-1) × (-3) =-81 [an = a + (n-1)d]
⇒ -3 (n-1) = -81 -21=-102
⇒ `n-1 = 102/3 = 34`
⇒ n= 34+1=35
Hence, the 35th term of the given AP is -81.
APPEARS IN
संबंधित प्रश्न
Ramkali required Rs 2,500 after 12 weeks to send her daughter to school. She saved Rs 100 in the first week and increased her weekly saving by Rs 20 every week. Find whether she will be able to send her daughter to school after 12 weeks.
What value is generated in the above situation?
The sum of n, 2n, 3n terms of an A.P. are S1 , S2 , S3 respectively. Prove that S3 = 3(S2 – S1 )
Determine the A.P. whose 3rd term is 16 and the 7th term exceeds the 5th term by 12.
Find the sum of the following APs.
0.6, 1.7, 2.8, …….., to 100 terms.
In an AP: Given a = 5, d = 3, an = 50, find n and Sn.
Find the sum of first n odd natural numbers
The 7th term of the an AP is -4 and its 13th term is -16. Find the AP.
Divide 24 in three parts such that they are in AP and their product is 440.
Find the sum of first n even natural numbers.
If the sum of first p terms of an AP is 2 (ap2 + bp), find its common difference.
Let there be an A.P. with first term 'a', common difference 'd'. If an denotes in nth term and Sn the sum of first n terms, find.
Which term of the sequence 114, 109, 104, ... is the first negative term?
If the sum of n terms of an A.P. is 2n2 + 5n, then its nth term is
If four numbers in A.P. are such that their sum is 50 and the greatest number is 4 times, the least, then the numbers are
Let the four terms of the AP be a − 3d, a − d, a + d and a + 3d. find A.P.
Obtain the sum of the first 56 terms of an A.P. whose 18th and 39th terms are 52 and 148 respectively.
If 7 times the seventh term of the AP is equal to 5 times the fifth term, then find the value of its 12th term.
If the last term of an A.P. of 30 terms is 119 and the 8th term from the end (towards the first term) is 91, then find the common difference of the A.P. Hence, find the sum of all the terms of the A.P.
Find the sum of first 16 terms of the A.P. whose nth term is given by an = 5n – 3.
Find the sum of first 25 terms of the A.P. whose nth term is given by an = 5 + 6n. Also, find the ratio of 20th term to 45th term.
