а)
x+2/x+3 - x-1/x=
=2/x+3-1/x=
=3+1/x=(3x+1)/x
б)
2y- 4y²/2y-1 -1=
=2y-2y-2=-2
в)
5a²/5ab-b² - b/25a-5b=
=5a²/(b(5a-b)) - b/(5(5a-b))=
=(25a^2 -b^2)/(5b(5a-b))=
=(5a -b)(5a+b)/(5b(5a-b))=
=(5a+b)/(5b)
г)
x²/x³-x + 1/2-2x =
=x^2/(x^3-x) + 1/(2-2x)=
=x/(x^2-1) + 1/(2*(1-x))=
=x/(x^2-1) - 1/(2*(x-1))=
=(2x-(x+1)/(2(x^2-1))=
=(x+1)/(2(x^2-1))=
=1/(2(x+1))