Learn all Concepts of Chapter 5 Class 10 (with VIDEOS). Check - Arithmetic Progressions - Class 10

Last updated at May 29, 2018 by Teachoo
Transcript
Ex 5.2 ,4 Which term of the A.P. 3, 8, 13, 18, is 78? 3, 8, 13,18, We need to find which term is 78 an = a + (n 1) d Hence, an = 78 a = 3 d = 8 3 = 5 Putting these in formula an = a + (n 1) d 78 = 3 + (n 1) 5 78 3 = (n 1) 5 75 = (n 1) 5 75/5 = (n 1) 15 = n 1 n 1 = 15 n = 15 + 1 n = 16 So, the 16th term of A.P. is 78
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