We know that x=t/(t+1) and y=1/(t^2-t)
(dy)/(dx)=(dy)/(dt)-:(dx)/(dt)
(dy)/(dt)=((t^2-t)d/dt[1]-1d/dt[t^2-t])/(t^2-t)^2
color(white)((dy)/(dt))=(0(t^2-t)-1(2t-1))/(t^2-t)^2
color(white)((dy)/(dt))=(-2t+1)/(t^2-t)^2
(dx)/(dt)=((t+1)d/dt[t]-td/dt[t+1])/(t+1)^2
color(white)((dx)/(dt))=(1(t+1)-t(1))/(t+1)^2
color(white)((dx)/(dt))=(t+1-t)/(t+1)^2
color(white)((dx)/(dt))=1/(t+1)^2
(dy)/(dx)=((-2t+1)/(t^2-t)^2)/(1/(t+1)^2)
color(white)((dy)/(dx))=((t+1)^2(-2t+1))/(t^2-t)^2