voila je dois calculer -2/5*(3/4+9/28)

Salut ,

[tex]E = - \frac{2}{5} * ( \frac{3}{4} + \frac{9}{28} ) = - \frac{2}{5} * \frac{84+36}{112} = - \frac{2}{5} * \frac{15}{14} = -\frac{30}{70} = - \frac{3}{7} [/tex]

Bonne soirée !

 -2/5*(3/4+9/28)
-2/5 * ( 21/28 +9/28)
-2/5 * 30/28
-60/140
-3/7