If the function f (x) = x ^ (n ^ 2-3n) (M belongs to Z) is even and monotone decreasing on (0, + ∞), then n =,

If the function f (x) = x ^ (n ^ 2-3n) (M belongs to Z) is even and monotone decreasing on (0, + ∞), then n =,

A: m should mean n
The function f (x) = x ^ (n ^ 2-3n) (M belongs to Z) is even and monotone decreasing on (0, + ∞)
If f (x) is even function, then n ^ 2-3n is even (including negative even or 0)
n^2-3n=(n-3)n
If n is even, then n-3 is odd and n ^ 2-3n = (n-3) n is even
If n is odd, then n-3 is even and n ^ 2-3n = (n-3) n is even
So: for any n belonging to Z number, n ^ 2-3n is even
F (x) = x ^ (n ^ 2-3n) is a monotone decreasing function when x > 0
Then n ^ 2-3n is a negative even number
So: n ^ 2-3n