my question I will mark as you brain list
A Polynomial is an equation in which variable x has positive integral power and the coefficient of x is not equal to zero.
According to this,
(i) and (ii) are the only Polynomials.
(iii) variable t has fractional power (i.e 1/2).
(iv) variable y has negative integral power.
(v)The question asks about polynomial in one variable. If y and t are taken as variables then this is not a polynomial in one variable.