a) (a/3 - a/4) 2/a^2 = (4a/12 - 3a/12) 2/a^2 = (a/12) * 2/a^2 = 2a/12a^2 = 1/6a
б) a - 1/3a : (1 - 1/a) = a - 1/3a * a/(a-1) = a - a/3 = 2a/3
в) (1+y/x) : (1-y/x) = (x+y) / x : (x-y) / x = x(x+y) / x(x-y) = (x^2 + xy) / (x^2 - xy)
a) (a/3 - a/4) 2/a^2 = (4a/12 - 3a/12) 2/a^2 = (a/12) * 2/a^2 = 2a/12a^2 = 1/6a
б) a - 1/3a : (1 - 1/a) = a - 1/3a * a/(a-1) = a - a/3 = 2a/3
в) (1+y/x) : (1-y/x) = (x+y) / x : (x-y) / x = x(x+y) / x(x-y) = (x^2 + xy) / (x^2 - xy)