u=-(sint +sin 3t +=sin 5t+-sin 7t+sin 9t) 3 5 (t =(sint+ sin 3t + sin 5t +-sin7t + 3sin9 ) 9 1 sin7 7 1 sin5 5 1 sin3 3 1 (sin 4 u t + t + t + t + t  = sin7 ) 7 1 sin5 5 1 sin3 3 1 (sin 4 ( ) + + + +  u t = t t t t