3 x x 3 x 2 x + 1 3 x 2 2 x 2 + x 2 4 x 2 x 2 2 x + 1 x 2 + 1 2 x =

= 3 x ( x 1 ) 2 ( x + 1 ) + 3 x 2 ( x 1 ) ( x + 1 ) x 2 2 ( x 1 ) 2 x + 1 ( x 1 ) 2 =

= 6 x + 3 x ( x 1 ) ( x + 1 ) ( x 2 ) 2 ( x + 1 ) ( x + 1 ) 2 ( x 1 ) 2 ( x + 1 ) =

= 6 x + 3 x 2 3 x x 2 + 2 x x + 2 2 x 2 2 x 2 x 2 2 ( x 1 ) 2 ( x + 1 ) =

( 3 1 2 ) x 2 + ( 6 3 + 2 1 2 2 ) x + ( 2 2 ) 2 ( x 1 ) 2 ( x + 1 ) =

= 0 2 ( x 1 ) 2 ( x + 1 ) = 0