Finding nth term from end
Finding nth term from end
Last updated at April 16, 2024 by Teachoo
Ex 5.2, 17 Find the 20th term from the last term of the A.P. 3, 8, 13, …, 253 Given AP 3, 8, 13, …, 253 Now, 20th term from last term of AP 3, 8, 13, …, = 20th term of AP 253, 248, 243, …., 8, 3 Thus, our AP is 253, 248, 243, …., 8, 3 Here a = 253 d = 248 – 253 = −5 We need to find 20th term n = 20 Now, an = a + (n – 1) d Putting values an = 253 + (20 – 1) × (−5) an = 253 + 19 × (−5) an = 253 − 95 an = 158 So the 20th term from the Last is 158