For each trinomial (quadratic expression), given below, find whether it is factorisable or not.
Factorise, if possible.
\begin{aligned}
&\text { (i) }\\
&x^{2}-3 x-54
\end{aligned} \begin{aligned}
&\text { (ii) }\\
&2 x^{2}-7 x-15
\end{aligned} \begin{aligned}
&\text { (iii) }\\
&2 x^{2}+2 x-75
\end{aligned}
\begin{aligned}
&\text { (iv) }\\
&3 x^{2}+4 x-10
\end{aligned}
\begin{aligned}
&(\mathrm{v})\\
&x(2 x-1)-1
\end{aligned}