Question

if an AP the sum of n term is 3n^2/2+13n/2 find a 25​

Answer 1

Answer:

Step-by-step explanation:

Sn=3n2/2+13n/2

S1=3x1x1x/2+13x1

   =3/2+13/2

   =16/2

   = 8

S1=a1=8

S2=3x2x2/2+13x2/2

   =12/2+26/2

   =38/2

   =19

S2-S1=a2

19-8=11

a2=11

a2-a1=d

11-8=3

d=3

a25=a+24d

     =8+24x3

     =8+72

     =80

   =