Exercice 1
Calculer : \(\frac{-5}{6}\times\frac{9}{10}\) ; \(\frac{-7}{4}\times\frac{-8}{21}\) ; \(-3\times\frac{5}{12}\).
Correction
\(-\frac{45}{60} = -\frac34\) ; \(\frac{56}{84} = \frac23\) ; \(-\frac{15}{12} = -\frac54\).
Exercice 2
Donner l'inverse de : \(\frac{-3}{7}\) ; \(-5\) ; \(0{,}25\).
Correction
\(-\frac73\) ; \(-\frac15\) ; \(4\).
Exercice 3
Calculer : \(\frac{-6}{5}\div\frac{3}{10}\) ; \(\frac{2}{3}\div(-4)\) ; \(\frac{\frac{-1}{2}}{\frac{3}{4}}\).
Correction
\(\frac{-6}{5}\times\frac{10}{3} = -4\) ; \(\frac23\times\frac{-1}{4} = -\frac16\) ; \(-\frac12\times\frac43 = -\frac23\).
Exercice 4
Calculer en respectant les priorités : \(A = \frac{1}{3} - \frac{2}{3}\times\frac{-3}{4}\) et \(B = \left(\frac{1}{3} - \frac{2}{3}\right)\div\frac{-3}{4}\).
Correction
\(A = \frac13 + \frac12 = \frac56\). \(B = -\frac13\times\frac{-4}{3} = \frac49\).