X/4 is polynomial function???

No, X/4 is not a polynomial function. A polynomial function is a function that can be written in the form f(x) = a_nx^n + a_(n-1)x^(n-1) + ... + a_1x + a_0, where a_n, a_(n-1), ..., a_1, a_0 are constants and n is a non-negative integer. In the expression X/4, the variable X is not raised to any power, so it does not fit the definition of a polynomial function.