For this problem, we know d = 6 because (11 - 5) = (17 - 11) = (23 - 17) = 6
Now, we have to use the formula:
[tex] a_{n} = a_{1} + (n-1)d[/tex]
For this problem, d = 6 and a(base1) is 5, so plug it in like this:
[tex] a_{n} = 5 + (n - 1)(6)[/tex]
To simplify, all you have to do is distribute the six and reduce like so:
[tex] a_{n} = 5 + ((6*n)-(6*1)) \\ a_{n}=5 + 6n - 6 \\ a_{n} = 6n-1 [/tex]
So, here's your answer:
[tex]a_{n} = 6n-1[/tex]
Hope this helps!
