1) a/(a -b) - (a -b)/(a +b) =(a(a+b) -(a-b)(a-b)) /(a-b)(a+b) =(a²+ab -(a²-2ab+b²)) /(a-b)(a+b) =(a²+ab-a²+2ab-b²) /(a-b)(a+b) =(3ab -b²) /(a²-b²)
2) =2(x-y)/y *3y²/(x-y)(x+y) =2(x -y)*3y² /y*(x -y)(x +y) =6y/(x+y)
3) (3v5)² /15 =9*5 /15 =9/3 =3
значок v обозначает корень