Factorise the following quadratic polynomials by splitting the middle term

$6 x^{2}+7 x-20$

Expand

$(2 x+3 y+5)^{2}$

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

$t^{2}$

Find the value of the polynomial $x^{2}-7 x+12$ at.

$x=3$

Factorise :

$a^{3}-2 \sqrt{2} b^{3}$