Réponse :
Il faut transformer les divisions en multiplications par l'inverse : [tex]\frac {a}{b} : \frac {c} {d} = \frac {a}{b} \times \frac {d} {c}[/tex]
Et pour les formes fraction fois un nombre : [tex]\frac {a} {b} \times c = \frac{a}{b} \times \frac {1}{c}[/tex]
Explications étape par étape :
50)
a) [tex]\frac{-7}{6} : \frac{3}{4} = \frac{-7}{6} \times \frac {4}{3} = \frac{-7 \times 4} {6 \times 3} = \frac {-28}{18} = \frac{-14}{9}[/tex]
b) [tex]\frac {3}{8} : \frac {-3} {4} = \frac {3 \times 4}{8 \times -3} = \frac {12}{-24} = \frac {1 \times 12}{-2 \times 12} = \frac {1} {-2} = \frac {-1}{2}[/tex]
c)[tex]\frac {-5} {9} : \frac {-8} {3} = \frac {-5 \times 3} {9 \times -8} = \frac {-15} {-72} = \frac {-1 \times 15} {-1 \times 72} = \frac {15}{72} = \frac {5} {24}[/tex]
51)
a)[tex]\frac {1} {5} \times (-3) = \frac {1} {5} \times \frac {1} {-3} = \frac {1 \times 1} {5 \times (-3)} = \frac {1} {-15} = \frac {-1} {15}[/tex]
b)[tex]\frac {3}{8} : (-6) = \frac {3} {8 \times (-6)} = \frac {3} {-48} = \frac {1 \times 3} {3 \times -16} = \frac {1} {-16} = \frac {-1} {16}[/tex]
c)[tex]- \frac{16}{8} : 5 = \frac {-16}{8} : 5 = \frac {-16} {8 \times 5} = \frac {-16} {40} = \frac {-2 \times 8} {5 \times 8} = \frac {-2} {5}[/tex]
