Which is and isn't a polynomial

4/x^4+3/x^2-2/x^2-1

^4√x-^3√x+4√x-8x+16

x^3-7x^2+9x-5x^4-20

x^5-5x^4+4x^3-3x^2+2x-1

3x^2-5x^4+2x-12

x^-5-5x^-4+4x^-3-3x^-2+2x^-1-1

First-person (only if there are 2 people obviously) will get brainliest

Number 3, 4, and 5 are polynomials

Step-by-step explanation:

Polynomials do not contain fractions as in expression 1 nor radicals as in expression 2.

Also they do not contain negative exponents as in expression 6.

Polynomials contain integer coefficients only.