Expand the following:

$\left(4-\frac{1}{3 x}\right)^{3}$

For polynomial $p(x)=x^{3}-3 x^{2}+8 x+12$, $p(-1)=\ldots \ldots \ldots$

Expand

$(2 a+3 b)^{2}$

Find the value of each of the following polynomials at the indicated value of variables

$p(t)=5 t^{2}-11 t+7$ at $t=a$

Classify the following as a constant, linear,quadratic and cubic polynomials:

$3 x^{3}$