Réponse :
[tex]\overrightarrow{CD} = \left(\begin{array}{cc}x_D - (-1)\\y_D - 6\end{array}\right) = \left(\begin{array}{cc}x_D +1\\y_D - 6\end{array}\right) \\3\overrightarrow{AB} = 3 \left(\begin{array}{cc}-2-4\\1-(-2)\end{array}\right) = 3 \left(\begin{array}{cc}-6\\3\end{array}\right) = \left(\begin{array}{cc}-18\\9\end{array}\right)[/tex]
Ainsi,
[tex]x_D + 1 = - 18 \iff x_D = -19\\y_D - 6 = 9 \iff y_D = 15[/tex]
Donc [tex]D(-19;15)[/tex]
