WebMar 22, 2024 · Transcript. Ex 9.2,13 If the sum of n terms of an A.P. is 3n2 + 5n and its mth term is 164, find the value of m. Let a1, a2, … an be the given A.P Given, Sum of n terms = 3n2 + 5n Sn = 3n2 + 5n Putting n = 1 in (1) S1 = 3 × 12 + 5 × 1 = 3 × 1 + 5 × 1 = 3 + 5 = 8 Sum of first 1 terms = First term ∴ First term = a1 = S1 = 8 Sn = 3n2 + 5n …(1) Putting n = 2 in … WebOct 7, 2024 · Sum of first n terms of the A.P = 3n² - 2n The A.P The 19th term of the A.P First we have to find the A.P Here sum of n terms is given as 3n² - 2n Hence sum of first term = First term (a₁) First term = 3 × 1² - 2 × 1 First term = 3 - 2 First term = 1 Hence first term of the A.P is 1 Now the sum of 2 terms is given by
In an arithmetic progression the sum of the first n …
WebMar 29, 2024 · Similarly find the 3rd, the 10th and the nth terms. Given Sn = 4n – n2 Taking n = 1 S1 = 4 × 1−12 = 4 – 1 = 3 ∴ Sum of first term of AP is 3 Taking n = 2 in Sn S2 = 4×2−2^2 S2 = 8 – 4 S2 = 4 ∴ Sum of first 2 terms is 4 But sum of first term will be the first term So, First term = a = 3 Finding 2nd term Sum of first 2 terms = 4 ... WebMar 8, 2024 · The sum of first n terms of an AP is +5n. To find: Which Term of AP is 152. The sum of first 20 terms . Explanation: The sum of first 20 terms .= +5n. = +5×20 = 3 × 400 + 100 = 1300 Which Term of AP is 152. = +5n. = 3×1+5×1 = 8 That is first number = 8 = +5n. = 3 × 2² +5×2 = 12+10 =22 = + 22 = 8+ = 22-8 = 14 Common difference = - = 14-8 = 6 iowa elections 2022 david young
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WebAug 28, 2024 · Let the sum of n terms be given by Sn so Sn = 3n²/2+ 5n/2 S1 = 3 (1)²/2 + 5 (1)/2 = 3/2+5/2 => 4 so 1st term is 4 say 'a' Now S2 = 3 (2)²/2 + 5 (2)/2 = 6+5 => 11 Now a2 … WebApr 10, 2024 · Sum of first n terms of an AP S n = n 2 [ 2 a + ( n − 1) d] Where a =1st term & d =common difference Or, S n = n 2 [ a + a n] If there are only n terms in an AP, then a n =l, l=last term We will put n=1, 2 in the sum formula and evaluate the first and second term of the A.P. Then we can easily derive the common difference. By putting all these in WebFind the rth term of the AP, the sum of whose first n terms is (3n2 + 2n). Given: The sum of first n terms. To Find: The rth term. Let the first term be a and common difference be d Put n = 1 to get the first term a = S1 = 3 + 2 = 5 Put n = 2 to get a + (a + d)2a + d = 12 + 4 = 1610 + d = 16d = 6tr = a + (r – 1)d iowa election results rob sands