Помогите даю 25 баллов

A) [(a^2+b^2) / ab +2)*ab / (a+b) = [(a^2+2ab+b^2) / ab]*ab / (a+b) =
   = [(a+b)^2 / ab]*ab / (a+b) = a+b

б) [(x+2) / (x^2+2x+4) - (6x-13) / (x^3-8)]* [(2x^2+4x+8) / (3-x)] =
   =[(x+2) / (x^2+2x+4) - (6x-13) / (x-2)(x^2+2x+4)]*[2(x+2)^2 / (3-x)] =
   = {[(x+2)(x-2) - 6x+13] / (x-2)(x+2)^2}*[2(x+2)^2 / (3-x)] =
   = (x^2-4-6x+13)*2 / (x-2)(3-x) = 2(3-x)^2 / (x-2)(3-x) = 2(3-x) / (x-2)

a2) [(a^2+b^2 / 2ab - 1]*[ 2ab / (a-b)] =
    = [(a^2-2ab+b^2) / 2ab]*[2ab / (a-b)]= (a-b)^2 / (a-b) = a-b

б2) [(x-2) / x^2-2x+4) - (2x - 5) / (x^3+8)]*[(3x^2-6x+12) / (1-x)] =
   = [(x-2) /( x-2)^2 - (2x - 5) / (x+2)(x^2-2x+4)]*[3(x^2-2x+4) / (1-x)] =
   = [(x-2) / (x-2)^2 - (2x - 5) / (x+2)(x-2)^2]*[3(x^2-2x+4) / (1-x)] =
   = [(x-2) / (x-2)^2 - (2x - 5) / (x+2)(x-2)^2]*[3(x-2)^2 / (1-x)] =
   =[{(x-2)(x+2) -2x +5} / (x-2)^2 (x+2)]*[3(x-2)^2 / (1-x)] =
   = [{(x^2-4-2x+5} / (x-2)^2 (x+2) ]*[3(x-2)^2 / (1-x)] =
   =[3(x^2-2x+1)] / [(x+2)(1-x)] = [3(1-x)^2] / [(x+2)(1-x)] = [3(1-x)] / (x+2)