Answer:
Solution given
n th term[tn]=?
1st term =a
difference =d
we have
t2=9
a+(n-1)d=9
a+(2-1)d=9
a+d=9
a=9-d..................[1]
again
t4=25
a+(n-1)d=25
a+(4-1)d=25
now
substituting value of a
9-d+3d=25
2d=25-9
d=16/2
d=8
substituting value of d in equation 1.
,a=9-8
a=1
we have
tn term =a+(n-1)d=1+(n-1)8=1+8n-8=8n-7
n th term =8n-7