Question

ap = 6 , 12,18,24 ,... ,120 . find sum of nth term

Answer 1

Hii ☺!!



AP = 6 , 12 , 18 , 24 , ...120.




Here,


First term ( a ) = 6


Common difference ( d ) = 6



Last term ( Tn ) = 120


a + ( n - 1 ) × d = 120


6 + ( n - 1 ) 6 = 120



6 + 6n - 6 = 120


6n = 120


n = 20.




Therefore,

Sn = n/2 × ( First term + Last term )



S20 = 20/2 × ( 6 + 120 )




=> 10 × 126



=> 1260.