Factorise :

$6 x^{2}+7 x-3$

The following expressions are polynomials? Justify your answer:

$1-\sqrt{5 x}$

Which one of the following is a polynomial?

Factorise

$8 x^{3}-26 x^{2}+13 x+5$

Give an example of a polynomial, which is:

$(i)$ monomial of degree $1$

$(ii)$ binomial of degree $20$

$(iii)$ trinomial of degree $2$