NB: The following uses the notation n^2 to mean 'n-squared'
Let's compare the first sequence to the square numbers which are, of course, 1, 4, 9, 16, 25, 36, . . . n^2
It's not difficult to see that the numbers in the sequence are simply 1 greater than the square numbers. So the nth term will simply be n^2 + 1
Try the same trick with the second sequence. Initially there doesn't seem to be an easy connection between the square numbers and those in the sequence but if you start the square numbers at 4 (instead of 1) the list is 4, 9, 16, 25, 36, . . . (n+1)^2
To change that list to the required sequence we simply need to subtract 6 from each term. So the nth term is (n+1)^2 -6
I suspect that you've mis-typed something in the 3rd sequence, because I can't make any sense of it.
For the last one you really do need to look at NazNomadd's link. Check that you understand what a, d and c are in the formula
nth term = a + (n - 1)d + ½(n - 1)(n - 2)c
Then enter the correct terms into that formula and simplify it, to get 2n^2 -5n + 5
Chris