1. 1)x/y^2-1/x=(x^2-y^2)/(xy; 2)...=(x^2-y^2)/(x^2y^2); 3)(x^2-y^2)/(xy) : (x^2-y^2)/(x^2y^2)=((x^2-y^2)x^2y^2 ) /((x^2-y^2)/xy)=xy.
2. 1) ( 2m^2 /(4+m)) - m=((2m^2-m(4+m)) / (4+m)=(2m^2-4m-m^2) /(4+m)=(m^2-4m) /(4+m)=(m(m-4)) /(m+4);
2)((4+m) / (4-m)) *(m(m-4)) /(m+4)=((4+m)*m(m-4)) /((4-m)*(m+4))=-m