`33/x = ( 1-1/16) .( 1-1/25) .( 1-1/36)  ...  ( 1-1/81) xx ( 1-1/100)`

`33/x=15/16.``24/25``.``35/36``...``80/81``.``99/100`

`33/x=`$\frac{15.24.35...80.99}{16.25.36...81.100}$

`33/x=`$\frac{(3.5).(4.6).(5.7)...(8.10).(9.11)}{(4.4).(5.5).(6.6)...(9.9).(10.10)}$

`33/x=`$\frac{(3.4.5...8.9).(5.6.7..10.11)}{(4.5.6...9.10).(4.5.6...9.10)}$

`33/x=3/10``.``11/4`

`33/x=33/40`

`=>x=40`

Vậy `x=40`