Hi, To solve my problem, I finally used a loop to draw a grid. Fabrice \starttext \start \switchtobodyfont[small] \startMPcode path p ; u := 2cm ; v:= 1cm ; p := (-u,-5v)--(3u,-5v)--(3u,4v)--(-u,4v)--cycle ; drawoptions(withpen pencircle scaled 0.5pt withcolor \MPcolor{mycolor}); for i=-u step u until 3u : draw (i,-5v)--(i,4v) ; endfor ; for i=-5v step v until 4v : draw (-u,i)--(3u,i) ; endfor ; drawoptions(withpen pencircle scaled 1pt) ; drawarrow (-u,0)--(3u,0) ; drawarrow (0,-5v)--(0,4v) ; draw (u,-0.05v)--(u,0.05v) ; draw (-0.025u,v)--(0.025u,v) ; draw curvedfunction ("x", "3*x*x-5*x+1", -1, 3, 0.01) xyscaled (u,v) withcolor red ; draw curvedfunction ("x", "-5*x+1", -1, 3, 0.01) xyscaled (u,v) withcolor blue ; draw curvedfunction ("x", "7*x-11", -1, 3, 0.01) xyscaled (u,v) withcolor green ; label.bot(btex $x$ etex,(2.97u,-0.1v)) ; label.rt(btex $y$ etex,(0.01u,3.9v)) ; label.llft("0",(0,0)) ; label.urt("A",(0,v)) ; dotlabel("",(u,-4v)) ; label.rt("C",(1.02u,-4v)) ; dotlabel.lrt("B",(2u,3v)) ; label.bot("1",(u,0)) ; label.lft("1",(0,v)) ; clip currentpicture to p ; \stopMPcode \stop \stoptext