input courbescp13;

beginfig(1);
  cadre((0,0),(18,8));
  draw grille(1) withcolor gris;
  origine((9,4));
  unites(4,2);
  draw axes;
  graduationx(btex 1 etex,1);
  graduationy(btex 1 etex,1);
  draw courbe1(-2.25,2.25,100,2*x);
  draw courbe2(-2.25,2.25,100,2-x);
  draw courbe3(-2.25,2.25,100,2+2*x);
  draw courbe4(-2.25,2.25,100,x**2-2*x-1);
  draw courbe5(-2.25,2.25,100,-0.5*x);
  draw courbe6(-2.25,2.25,100,0.25*x-1);
  draw labelise1(btex courbe 1 etex,0.3);
  draw labelise2(btex courbe 2 etex,0.6);
  draw labelise3(btex courbe 3 etex,0.4);
  draw labelise4(btex courbe 4 etex,0.31);
  draw labelise5(btex courbe 5 etex,0.2);
  draw labelise6(btex courbe 6 etex,0.2);
endfig;
end