The curve \(C\) has equation \(y=\frac{{{x}^{2}}+5}{\lambda x+1}\), where \(\lambda \) is a non-zero constant.
Obtain the equations of the asymptotes of \(C\).
Show that \(C\) has exactly two points at which \(\frac{\mathrm{d}y}{\mathrm{d}x}=0\).
Draw a sketch of \(C\) to illustrate the case \(\lambda >0\), and a separate of \(C\) to illustrate the case \(\lambda <0\).
Find the set of values of \(\lambda \) for which the line \(y=4x\) and \(C\) has at least one point in common.