Prove the following properties of the Bessel functions of the first kind:
\({ \frac { d } { d x } } \left( x ^ { \nu } J _ { \nu } ( x ) \right) = x ^ { \nu } J _ { \nu - 1 } ( x )\)
\({ \frac { d } { d x } } \left( x ^ { - \nu } J _ { \nu } ( x ) \right) = - x ^ { - \nu } J _ { \nu + 1 } ( x )\)
\(\frac { d } { d x } J _ { \nu } ( x ) = \frac { 1 } { 2 } \left( J _ { \nu - 1 } ( x ) - J _ { \nu + 1 } ( x ) \right)\)
\(J _ { \nu - 1 } ( x ) + J _ { \nu + 1 } ( x ) = \frac { 2 \nu } { x } J _ { \nu } ( x )\)