How come x^4/3 is a ploynomial, but 3/x^4 isn't?

Answer 1

this site gives a good explanation.

http://www.purplemath.com/modules/polydefs.htm

basically, in a regular polynomial the exponents must be whole numbers

since 3/x^4 = 3x^-4 , this violates that definition

Answer 2

x cannot have a negative power in a polynomial by definition.

http://www.merriam-webster.com/dictionary/polynomial