Question

In a sequence, if T n + 1 = 4n + 5 then T n is

Answer 1

Putting n=1 
$T_{1}$ = 8
Putting n=2 
$T_{2}=12$ 
$d= T_{2}-T_{1}=12-8=4$
a=8
d=4
$T_{n}= a + (n-1)d = 8+(n-1)4= 8+ 4n - 4 = 4+4n = 4(n+1)$