Question

Question 15 For what value of n, are the n th terms of two APs 63, 65, 67, and 3, 10, 17, … equal

Class 10 - Math - Arithmetic Progressions Page 106

Answer 1

63, 65 , 67, ......... n terms
a = 63 , d = 2
Tn = a + ( n -1)d
= 63 + ( n -1)2
= 61 + 2n

3, 10 , 17 ..............n terms
a = 3 , d = 7
T'n = 3 + ( n -1 ) × 7
= -4 + 7n

A/C to question ,
Tn = T'n
61 + 2n = -4 + 7n
65 = 5n
n = 13

Answer 2

hopes i helped.................