(2) Find the common difference and 15 th term of an A.P 125 , 120 ,115 , 110 , ……….….

Solution :

First term = 125

 a = 125

Common difference = t2 – t1

 = 120 – 125

 = -5

General term of an A.P

(tn) =  a + (n - 1) d

15th term of the A.P  = 125 + (15 - 1) (-5)

=  125 + 14 (-5)

=  125 – 70

t₁₅   = 55

Hence, 15th term of A.P is 55