5.
$$y = \sin x \sinh x$$
- Show that \(\frac { \mathrm { d } ^ { 4 } y } { \mathrm {~d} x ^ { 4 } } = - 4 y\)
- Hence find the first three non-zero terms of the Maclaurin series for \(y\), giving each coefficient in its simplest form.
- Find an expression for the \(n\)th non-zero term of the Maclaurin series for \(y\).