Question

For what value of n are the n^th term of two AP , 63 , 65 , 67 ,…… and 3 , 10 , 17 ,…….equal?

Answer 1

In  the first series , a= 63, d =2
in second series, a= 3 , d= 7
nth term = a + (n -1)d
as both series have nth term same, so
63 +(n -1)2 = 3 + (n -1)7
⇒5(n -1) =60
⇒(n -1) = 12
⇒n =13

Answer 2

Answer:

Step-by-step explanation:

in case -1

a= 63

d=65-63=2

n=?

63+(n-1)2            =          (a+(n-1)d)

63+2n-2;

in case - 2

a= 3

d= 10-3=7

n=?

3+(n-1)7                  =         (a+(n-1)d)

3+7n-7;

by equaling both

63+2n-2 = 3+7n-7

61+2n = -4+7n

61+4= 7n - 2n

65 = 5n

n = 65 / 5

n = 13