Factorise
$x^{3}+12 x^{2}+39 x+28$
Expand
$\left(\frac{2 x}{3}+\frac{3 y}{4}\right)^{2}$
Find the value of the polynomial $3 x^{3}-4 x^{2}+7 x-5,$ when $x=-3$
If the polynomial $a x^{3}+4 x^{2}+3 x-4$ and polynomial $x^{3}-4 x+a$ leave the same remainder when each is divided by $x-3,$ find the value of $a$.
Factorise the following quadratic polynomials by splitting the middle term
$12 x^{2}+23 x+5$