Arithmetic progression class 10 Maths CBSE Ncert solutions

 Question 2: 

           Find the 20^th term from the last term of the AP: 3, 8,13,….,253

Another method :

Given :  AP: 3, 8,13,….,253.

  a = 253 

  d = 3 -8 ( if ask from the last term means go for t1 - t2 )

     = -5

 tn = a + (n-1)d

     = 253 + ( 20-1)(-5)

     = 253 + 19(-5)

     = 253 - 95

     = 158

20th term of  Ap is  158.