Write whether the following statements are True or False. Justify your answer.
$\frac{1}{\sqrt{5}} x^{\frac{1}{2}}+1$ is a polynomial
Factorise :
$x^{2}+9 x+18$
Factorise
$(x-2 y)^{3}+(2 y-3 z)^{3}+(3 z-x)^{3}$
Factorise
$6 x^{3}+7 x^{2}-14 x-15$
Write the coefficient of $x^{2}$ in the following polynomials
$5-7 x-3 x^{2}$