soluzione Calcolare (1 - 18 x2 + 9 ) · ( x x2 - x - 6 + x x2 + 5x + 6   -   1 x + 2 ) : ( 1 x + 2 + 1 x - 1 ) = = (1 - 18 x2 + 9 ) · ( x (x + 2)(x - 3) + x (x + 2)(x + 3)   -   1 x + 2 ) : ( 1 x + 2 + 1 x - 1 ) = = x2 + 9 - 18 x2 + 9 · x(x + 3) + x(x - 3) - (x - 3)(x + 3) (x + 2)(x - 3)(x + 3) : x - 1 + x + 2 x + 2 = = x2 + 9 - 18 x2 + 9 · x2 + 3x + x2 - 3x - x2 + 9 (x + 2)(x - 3)(x + 3) : x - 1 + x + 2 x + 2 = = x2 - 9 x2 + 9 · x2 + 9 (x + 2)(x - 3)(x + 3) : 2x + 1 x + 2 = = x2 - 9 x2 + 9 · x2 + 9 (x + 2)(x - 3)(x + 3) · x + 2 2x + 1 = = (x - 3)(x + 3) x2 + 9 · x2 + 9 (x + 2)(x - 3)(x + 3) · x + 2 2x + 1 = = 1 2x + 1