Dear friends, can I use Ryacas to solve the two equations X = a/(a+b) Y = (a+b)^2*(a+b+1)/(a*b) subject to a>0 and b>0 ? I'm on windows using latest R Best wishes Troels Ring Nephrology Aalborg, Denmark Jeg bruger BullGuard til at holde min computer ren. Prøv BullGuard gratis: www.bullguard.com