Evaluate $$$$f$($x$)$dx$$f$($x$)$dx$,$ where

f$($x$)=\{6$x$3,9$sin$($x$),$$$x$<00$x$$$.$f$($x$)=\{6$x$3,$$$x$<09$sin$($x$),0$x$$$.$

$$$$f$($x$)$dx$$f$($x$)$dx $=$