Bonjour,
[tex]\left\{\begin{array}{ccc}y&=&mx\\y&=&9x^2+3x+1\\\end{array}\right.\\\\9x^2+(3-m)x+1=0\\\\\Delta=(3-m)^2-36 \\\\\Delta=0\Longleftrightarrowm=9\ ou\ m=-3\\[/tex]
