I.a) (x+12)/(8x-7) + (2x-7)/(7-8x) = (x+12)/(8x-7) - (2x-7)/(8x-7) =
=(x+12-2x+7)/(8x-7) = (19-x)/(8x-7)
б) (11-x)/(5x-9) - (5x+4)/(9-5x) = (11-x)/(5x-9) + (5x+4)/(5x-9) =
(11-x+5x-4)/(5x-9) = (4x+7)/(5x-9)
II. a) (3x+11)/(x+4) + 9+2x)/(x+4) = (3x+11+9+2x)/(x+4) = (5x+20)/(x+4) =
= 5(x+4)/(x+4) =5
б) (7x-11)/(2x-5) + (x+4)/(5-2x) = (7x-11)/(2x-5) - (x+4)/(2x - 5) =
=(7x-11-x-4)/(2x-5) = (6x-15)/2x-5) = = 3(2x-5)/(2x-5) = 3
в) (5x-11)/(x-6) - (7+2x)/(x-6) = (5x-11-7-2x)/(x-6) = (3x-18)/(x-6) =
= 3(x-6)/(x-6) = 3
г) (4x-10)/(x^2-5xy) - (4y-2)/(xy - 5y^2) = (4x-10)/x(x-5y) - (4y-2)/y(x - 5y) =
= (4xy - 10y - 4xy + 2)/xy(x-5y) = (2x-10y)/xy(x-5y) =2(x-5y)/xy(x-5y) =
= 2/xy