WebBesides giving the explanation of In an A.P. if a=1,An=20 and Sn=399, then find the value of n.?, a detailed solution for In an A.P. if a=1,An=20 and Sn=399, then find the value of n.? has been provided alongside types of In an A.P. if a=1,An=20 and Sn=399, then find the value of n.? theory, EduRev gives you an ample number of questions to … WebQuestion If an AP has a = 1, a n = 20 and S n = 399, then find the value of n. Solution Compute the value of n: Formulae: The n th term of an AP is a n = a + n - 1 d and the sum of n terms of a series in an AP is S n = n 2 2 a + ( n - 1) d. Substitute a = 1, a n = 20 in the n th term of an AP formula.
In an A.P., if an = 1, a = 20 and Sn = 399, then n - Sarthaks
WebIn an AP, if a = 1, an = 20 and Sn = 399, then n is equal to (a) 19 (b) 21 (c) 38 (d) 42 Solution: Question 18: The sum of first five multiples of 3 is (a) 45 (b) 55 (c) 65 (d) 75 Solution: (a) The first five multiples of 3 are 3, 6, 9,12 and 15. Here, first term, a = 3, common difference, d = 6-3 = 3 and number of terms, n = 5 WebIf an A.P. has a = 1, t n = 20 and s n = 399, then value of n is : A. 20 B. 32 C. 38 D. 40 Answer: Option C Solution (By Examveda Team) S n = 1 2 ( a + l) × n ⇒ 399 = ( 1 + 20) × n 2 ⇒ 399 × 2 = 21 × n ⇒ n = 399 × 2 21 ⇒ n = 19 × 2 ⇒ n = 38 Join The Discussion Related Questions on Progressions How many terms are there in 20, 25, 30 . . . . . . 140? simplify class 5
In an Ap, a=1, an=20, sn=399 then find n - Brainly.in
WebFeb 26, 2016 · Find an answer to your question In an AP, if a=1,an=20 and Sn= 399, then n=? yoyphcrazyp yoyphcrazyp 26.02.2016 Math Secondary School answered In an AP, if a=1,an=20 and Sn= 399, then n=? 2 See answers Cn u make the question little clear? Advertisement Advertisement Shree99 Shree99 WebTo find : n and 20th term from the end We have, l = a + (n – 1)d ⇒ 399 = 3 + (n – 1) × 4 ⇒ 399 – 3 = 4n – 4 ⇒ 396 + 4 = 4n ⇒ 400 = 4n ⇒ n = 100 So, there are 100 terms in the given AP Last term = 100th Second Last term = 100 – 1 = 99th Third last term = 100 – 2 = 98th And so, on 20th term from the end = 100 – 19 = 81st term raymond t murphy