Question

If a1 =7 and an= 3an-1 + 4 then find the value of a4. a

Answer 1

Solution

For this case we know that:

a1= 7

$a_n=3a_{n-1}+4$

Then for a4 we have:

$a_4=3a_3+4=3(3a_2+4)+4=9a_2+16=9(3a_1+4)+16=27a_1+36+16$

And then we can replace and we got:

a4= 27*7 +52= 241