Which of the following expressions are polynomials in one variable and which are not $?$ State reason for your answer. If the given expression is a polynomial, state whether it is a polynomial in one variable or not

$x^{2}+2 x y+y^{2}$

With the help of the remainder theorem, find the remainder when the polynomial $x^{3}+x^{2}-26 x+24$ is divided by each of the following divisors

$x-6$

Factorise each of the following

$64 x^{3}+125 y^{3}+240 x^{2} y+300 x y^{2}$

Determine the degree of each of the following polynomials:

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

Factorise the following:

$8 p^{3}+\frac{12}{5} p^{2}+\frac{6}{25} p+\frac{1}{125}$