Question

what is sum of 25terms whose nth term is 3n+2

Answer 1

3n+2 where as
25thterm =3{25}+2=25×3=75+2=77

Answer 2

nth term   = 3 n + 2

put n = 1 and 2

then we get  = 3 (1) +2 = 5

                      = 3(2) +2 = 8

 so, common difference is = 8-5 = 3

  S 25   = 25/2( (2(5) + (25-1) 3 )

 SO,,  S 25 = 25/2 (10 + 72)

     S 25 = 25/2 (82)

   S 25 = 25 * 41   = 1025

SO S 25 =  1025

HOPE IT HELPS YOU