2. Найдите значение выражения: 1) (2y-7)/(y²-9) - (y-10)/(y²-9) при y = 3,1; y = −2; 2) -(3c-5)/(4-c²) + (3-2c)/(c²-4) при с = 3; с = -3.

2. Найдите значение выражения:

1. 1)

   \[ \frac{2y-7}{y^2-9} - \frac{y-10}{y^2-9} = \frac{2y-7 - (y-10)}{y^2-9} = \frac{2y-7-y+10}{y^2-9} = \frac{y+3}{y^2-9} = \frac{y+3}{(y-3)(y+3)} = \frac{1}{y-3} \]

   При y = 3,1:

   \[ \frac{1}{3,1-3} = \frac{1}{0,1} = 10 \]

   При y = −2:

   \[ \frac{1}{-2-3} = \frac{1}{-5} = -0,2 \]

2. 2)

   \[ -\frac{3c-5}{4-c^2} + \frac{3-2c}{c^2-4} = -\frac{3c-5}{-(c^2-4)} + \frac{3-2c}{c^2-4} = \frac{3c-5}{c^2-4} + \frac{3-2c}{c^2-4} = \frac{3c-5+3-2c}{c^2-4} = \frac{c-2}{c^2-4} = \frac{c-2}{(c-2)(c+2)} = \frac{1}{c+2} \]

   При c = 3:

   \[ \frac{1}{3+2} = \frac{1}{5} \]

   При c = -3:

   \[ \frac{1}{-3+2} = \frac{1}{-1} = -1 \]