Question

In an ap the sum of 1st team 3n2/2+13n/2 find 25th term

Answer 1

 n =1

S1 = 3/2+13/2 = 16/2 =8

S2 = 12/2 + 26/2 = 6+13 = 19

S2 -S1= 19-8 = 11=a2

a2-a1 =d 

d= 11 -8 = 3

a25 = a+(25-1)d

        = 8 + (24 x3)

         = 72+8 =80