A polynomial is every function that looks like this:
f(x)=(An)*xⁿ + (An-1)*xⁿ⁻¹ +.....+A₁*x +A₀
So functions that are polynomials are:
3x²-5x⁴+2x-12,
x⁵-5x⁴+4x³-3x²+2x-1,
x⁻⁵-5x⁻⁴+4x⁻³-3x⁻²-1,
x³-7x²+9x-5x⁴-20.
And functions that are NOT polynomials:
4/x⁴ + 3/x³ - 2/x² -1,
⁴√x - ³√x + ⁴√x - 8x +16.
So the second picture is correct.