From the following polynomials find out which of them has $(x+1)$ as a factor
$x^{3}+10 x^{2}+23 x+14$
$(x+1)$ is a factor.
Factorise
$16 x^{2}-16 x-21$
Expand
$(2 x+5 y)^{2}$
$\left(\frac{x}{2}-\frac{2}{5}\right)^{2}$
$(3 x-2)(3 x-6)$
$(x+5 y)(x-5 y)$