For each of the following functions, decide whether it is even, odd, or neither. Enter E for an EVEN function, O for an ODD function and N for a function which is NEITHER even nor odd.

1. $f(x) = x^ {8 } - 6x^ {4 } +3x^ {2 }$
2. $f(x) = -5x^ {8 }- 3x^ {4 } -2$
3. $f(x) = x^ {-1 } + x^ {3 } +x^ {5 }$
4. $f(x) = x^ {8 } +3 x^ {4 } +2x^ {5 }$