5) (х+1-1)/(х-1)=х/(х-1)
(а^2+b^2+2ab)/(a+b) = (a+b)^2/(a+b) = a+b
6) (3-2)/6a = 1/6a
(m(m+n)+m(m-n)/(m-n)(m+n) = (m^2+mn+m^2-mn)/m^2-n^2 = 2m^2/m^2-n^2
4x/(x+y)(x-y) - 4/(x+y) = (4x - 4(x-y))/(x-y)(x+y) = (4x-4x+4y)/(x^2-y^2) = 4y/x^2-y^2
5a/(a-5) - 25/(a-5) = (5a-25)/(a-5) = 5(a-5)/(a-5) = 5