Factorise

$x^{3}+12 x^{2}+39 x+28$

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

$x=\frac{1}{2}$

Factorise the following quadratic polynomials by splitting the middle term

$x^{2}-3 x-40$

 

Expand

$(2 x-3)(2 x+5)$

Factorise

$x^{2}+4 y^{2}+25 z^{2}+4 x y-20 y z-10 z x$

From the following polynomials find out which of them has $(x-1)$ as a factor

$x^{3}+6 x^{2}-9 x-14$