A polynomial is defined as an expression which is composed of variables, constants and exponents, that are combined using the mathematical operations such as addition, subtraction, multiplication and division but is never division by a variable.
Therefore claim 4 is false.
When 2x is added, the resultant will be a polynomial.
when 2x is subtracted, the resultant will be a polynomial.
When multiplied by 2x also, the resutant will be a polynomial.