[tex] n^{\text{th}} \text{ term is } 5n+7 [/tex]
forget n for a while.
let's call it t .
The [tex] t^{\text{th}} \text{ term is } 5t+7 [/tex]
agreed? I don't think there should be a problem.
you're asked what's the [tex](t+1)^{\text{th}}[/tex] term.
let's call it u . so just like we did before,
[tex] u^{\text{th}} \text{ term is } 5u+7 [/tex]
but we know, [tex]u=t+1[/tex]
So, [tex]5u+7=5(t+1)+7=5t+12[/tex]
does that answer your question?
