Question

Which term of the AP, 3,10,17 will be 84 more than its 13th term?
 

Answer 1

Let the nth term be 84 more than the 13th term.
Now a/q,
a=3, d=10-3=7
So, 13th term= a+12d =3+12x7=87
Then nth term=84+87=171
171=a + (n-1)d
171=3 + (n-1)x7
171-3/7+1=n
168/7+1=n
24+1=25=n

Therefore 25th term of the ap will be 84 more than 13th term