Factorise the following quadratic polynomials by splitting the middle term

$12 x^{2}+23 x+5$

Factorise the following:

$25 x^{2}+16 y^{2}+4 z^{2}-40 x y+16 y z-20 x z$

Classify the following as linear, quadratic or cubic polynomial

$35 x^{2}-16 x-12$

Examine whether $2 x+3$ is a factor of $2 x^{3}+21 x^{2}+67 x+60$ or not.

Write the degree of each of the following polynomials

$x^{8}-6561$

Factorise

$144 x^{2}-289 y^{2}$