( x² + 2 - x² -2x ) ·(x -2) · ( x +2)
E = -----------------------------------------------
( x +2) ² · ( x +2 - 3)
(2 - 2x) · ( x -2)
E = ----------------------------------------
( x +2) · ( x -1 )
-2 · ( x - 1) · ( x - 2 )
E = -------------------------------------
( x + 2) · ( x -1)
E = ( -2x + 4 ) / ( x +2)