Question

a1 =3 and an=3an-1+1 nd n>1

Answer 1

if a is 3 d = -1
then A.P is 3,2,1,0,-1

Answer 2

a_(n) =3a_(n-1)+1

Using the given expression

a_2= 3a_1 +1= 3×3+1=10

Similarly

a_3 = 31

a_4=94

a_5=283