[tex]\\\\\\ Bonjour ; \\\\\\ a) \ \dfrac{5}{7} \times \dfrac{1}{3} \times \dfrac{-1}{2} = \dfrac{5\times 1 \times (- 1)}{7\times3\times 2} = \dfrac{- 5}{42} = - \dfrac{5}{42}\ . [/tex]
[tex]b) \ \dfrac{-3}{5} \times \dfrac{-1}{2} \times \dfrac{-2}{7} = \dfrac{(- 3)\times (- 1) \times (-2)}{5\times 2\times 7} = \dfrac{- 6}{70} = \dfrac{- 3}{35} = -\dfrac{3}{35} \ .[/tex]
