WebNov 11, 2011 · Find the sum of first n terms if an AP whose nth term is 5n-1. Hence find the sum of first 20 terms Asked by 11 Nov, 2011, 04:16: PM Expert Answer n th term = 5n - 1 Put n=1, we get 1 st term = 5-1 = 4 Hence sum of n terms = n (First term + nth term)/2 = n (4+5n - 1)/2 = n (5n +3)/2 Sum of 20 terms becomes, put n = 20 S 20 = 20 (5×20 +3)/2
in an A.P the sum of first n-terms is (5n^2)/2+3n/2 . Find the 17th ...
WebThe sum of the first n term sofa an AP is ( 3 n 2 2 + 5 n 2). Find its nth term and the 25th term Advertisement Remove all ads Solution Let S denotes the sum of first n terms of the AP. ∴ s n = ( 3 n 2 2 + 5 n 2) ⇒ s n - 1 = 3 ( n - 1) 2 2 + 5 ( n - 1) 2 = 3 ( n 2 - 2 n + 1) 2 + 5 ( n - 1) 2 = 3 n 2 - n - 2 2 ∴ n th term pf the AP , a n WebThe sum of first n terms of an A.P is given by S n=2n 2+3n. Find the sixteenth term of the A.P Easy Solution Verified by Toppr Sn= 2n(2a+(n−1)d) = 2n(2a−d)+n 22d=2n 2+3n ∴2= 2d⇒=4 and 22a−d=3 ∴2a=6+d=10 or, a=5. ∴a 16=a+(1+−1)d =5+15×4=65. Was this answer helpful? 0 0 Similar questions rbnb st lary
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WebGeneral term of an AP is given by: a n = S n - S (n - 1) Calculation: Given: S n = 5n 2 + 6n and m th tem is 301. a n = S n - S (n - 1) After solving above equation we get . a n = 5(n) 2 + 6(n) - [5(n - 1) 2 + 6(n - 1)] a n = 5n 2 + 6n - 5n 2 - 5 + 10n - 6n + 6. a n = 10n + 1 . For 1st term, put n = 1. So, a 1 = 10 × 1 + 1 = 11. For 2nd term ... WebIn an A.P the sum of first n terms is 3n2/2 + 13n/2. Find the 25th term arithmetic progression cbse class-10 1 Answer +1 vote answered Sep 30, 2024 by KajalAgarwal (45.2k points) selected Oct 1, 2024 by Vikash Kumar Best answer Given, Sn = 3n2/2 + 13n/2 ← Prev Question Next Question → Find MCQs & Mock Test JEE Main 2024 Test Series NEET Test … WebFormula to find the sum of AP when first and last terms are given as follows: S = n/2 (first term + last term) List of Arithmetic Progression Formulas The list of formulas is given in a tabular form used in AP. These formulas are useful to solve problems based on the series and sequence concept. Arithmetic Progressions Solved Examples rbnb thionville