Quy đồng mẫu thức hai phân thức: x+y / x^2 y +x^2 ; 2x-y /y+1

x-yx2y+x2=x-yx2(y+1);2x+yy+1=x2(2x-y)x2(y+1)

x+yx2y-x2=x+yx2(y-1);2x-yy+1=x2(2x-y)x2(y+1)

x+yx2y+x2=x+yx2(y+1);2x-yy+1=x2(2x-y)x2(y+1)

x+yx2y+x2=x+yx(y+1);2x-yy+1=2x-yx2(y+1)