Bonjour ,

Exercice 1 :

A :

[tex] \frac{2}{3} \times \frac{6}{4} = \frac{2 \times 6}{3 \times 4} = \frac{12}{12} = 1[/tex]

B :

[tex] \frac{ - 3}{5} \times \frac{4}{ - 7} = \frac{ - 3 \times 4}{5 \times ( - 7)} = \frac{ - 12}{ - 35} = \frac{12}{35} [/tex]

C :

[tex] \frac{4}{3} \times 12 = \frac{4}{3} \times \frac{12}{1} = \frac{4 \times 12}{3 \times 1} = \frac{48}{3} [/tex]

D :

[tex] \frac{2}{4} \times \frac{400}{200} = \frac{2 \times 400}{4 \times 200} = \frac{800}{800} = 1[/tex]