(i)
The degree of the polynomial is 2. It is quadratic in x.
So, it is quadratic polynomial.
(ii)
The degree of the polynomial is 1. It is a linear polynomial in x.
(iii)
The degree of the polynomial is 1.
It is linear a polynomial in x.
(iv) 3y
The degree of the polynomial is 1. It is linear in y.
(v)
The degree of the polynomial is 2. It is quadratic polynomial in t.
(vi)
The degree of the polynomial is 4. Therefore, it is bi-quadratic polynomial in t.