Question

value for n for which nth terms of two A.P.s,63,65,67....... and 3,10,17 are equal?

Answer 1

In first AP
                   63,65,67..........
a = 63
d = 2 
            an = a+(n-1)d
            an = 63+(n-1)2
            an = 63+2n-2
            an = 61+2n               .............(1)

 In second AP 
                       3,10,17 ......
a = 3
d = 7
             an = 3+7n-7
             an = 7n-4                      ....................(2)
 
                     from (1) and (2)
                      61+2n = 7n-4

                            5n = 65
                              n = 13  
              I think you mark as brain list

Answer 2

In the first Ap
first term =63
common difference=2
n th term of the given first AP is
An=a+(n-1)d
Placing the number in eq
An=63+(n-1)2
=63+2n-2
=61+2n......i

In second Ap
First term =3
Common difference=7
n th term of the given second AP
An=a+(n-1)d
Placing the numbers in the eq
=3+(n-1)7
=3+7n-7
=7n-4.......ii

61+2n=7n-4
61+4=7n-2n
65=5n
n=13
The 13 th term Of both AP is equal
Hope my answer helps u
Thanks
3:16