Classify the following as a constant, linear,quadratic and cubic polynomials:
$1+x+x^{2}$
Factorise the following quadratic polynomials by splitting the middle term
$6 x^{2}+7 x-20$
Factorise $: 49 x^{2}-121$
Expand
$(11 x+18)(11 x-18)$
Expand
$(3 x+5)^{2}$