Given first equation,
(1) 2x^⁴+12x+4
it's a polynomial of degree (4)
known as Tetra polynomial
(2) x^³+4x
it's a polynomial of degree (3)
known as cubic polynomial
(3) 3/x^⁴-6x³
it's not a polynomial because of power of X is (-4) which a negative
so it's not a polynomial
(4) x^⁴/3-6
it's a polynomial of degree (4)
known as Tetra polynomial