Question

Find the first 20 terms of sn ap whose nth term is an+b

Answer 1

Answer:

Given an A.P. whose nth term is given by, an = An + B We need to find the sum of first 20 terms. To find the sum of the n terms of the given A.P., we use the formula, Sn = n(a+l)2n(a+l)2 Where, a = the first term l = the last term, Putting n = 1 in the given an, we get a = A(1) + B = A + B For the last term (l), here n = 20 A20 = A(20) + B = 20A + B S20 = 202202((A + B) + 20A + B) = 10[21A + 2B] = 210A + 20B Therefore, the sum of the first 20 terms of the given A.P. is 210 A + 20BRead more on Sarthaks.com - https://www.sarthaks.com/654939/find-the-sum-of-first-20-terms-the-sequence-whose-nthterm-is-an-an-b