Сократите дробь и найдите ее значение: (ab+ac-2c-2b)/(b^2-c^2) при a=3; b=5,6; c=5,7.

\[\frac{ab + ac - 2c - 2b}{b^{2} - c^{2}} =\]

\[= \frac{a(b + c) - 2 \cdot (b + c)}{(b - c)(b + c)} = \frac{(b + c)(a - 2)}{(b - c)(b + c)} =\]

\[= \frac{a - 2}{b - c}\]

\[При\ a = 3;\ \ b = 5,6;\ \ c = 5,7:\]

\[\frac{3 - 2}{5,6 - 5,7} = \frac{1}{- 0,1} = - 10.\]