Даю 50 баллов срочно

a) (х - у)/(ху) - (х - z)/(xz) = [z (x - y) - y (x - z)] / (xyz) = (xz - yz - xy + yz)/(xyz) =

= (xz - xy)/(xyz) = [x(z - y)]/(xyz) = (z - y)/(yz) = 1/y  - 1/z;

б) (a - 2b)/(3b) - (b - 2a)/(3a) = [a (a - 2b) - b (b - 2a)]/(3ab) =

=  (a - 2ab - b + 2ab)/(3ab) = (a - b)/(3ab) = a/(3b) - b/(3a);

в)  (6a - 4b)/5 - (b + 7a)/3 - 2/1 = [3  (6a - 4b) - 5 (b + 7a) - 15 2]/15 =

= (18a - 12b - 5b - 35a - 30)/15 = (-17a - 17b - 30)/15 = - 17(a + b)/15 - 2.

a) (х - у)/(ху) - (х - z)/(xz) = [z (x - y) - y (x - z)] / (xyz) = (xz - yz - xy + yz)/(xyz) =

= (xz - xy)/(xyz) = [x(z - y)]/(xyz) = (z - y)/(yz) = 1/y  - 1/z

б) (a - 2b)/(3b) - (b - 2a)/(3a) = [a (a - 2b) - b (b - 2a)]/(3ab) =

=  (a - 2ab - b + 2ab)/(3ab) = (a - b)/(3ab) = a/(3b) - b/(3a)

в)  (6a - 4b)/5 - (b + 7a)/3 - 2/1 = [3  (6a - 4b) - 5 (b + 7a) - 15 2]/15 =

= (18a - 12b - 5b - 35a - 30)/15 = (-17a - 17b - 30)/15 = - 17(a + b)/15 - 2