Express \(\frac { 1 } { ( r + 2 ) r ! }\) in the form \(\frac { A } { ( r + 1 ) ! } + \frac { B } { ( r + 2 ) ! }\), where \(A\) and \(B\) are integers. [0pt]
[3 marks]
Hence find \(\sum _ { r = 1 } ^ { n } \frac { 1 } { ( r + 2 ) r ! }\). [0pt]
[2 marks]