Question

If a1 = 8 and an = 3an-1 then find the value of a4.

Answer 1

a_4= 216

1) Given that we have the first term and the Recursive Formula, let's find the fourth term of that Sequence

2) Let's find the second, the third to find the fourth since a Recursive formula depends on the prior term.

`\begin{gathered} a_1=8 \\ a_n=3a_(n-1) \\ a_2=3(8)\text{ =24} \\ a_3=3(24)=72 \\ a_4=3(72)\text{ =216} \end{gathered}`

3) Hence, the sequence is 8, 24, 72, 216 and the fourth term is 216