Calculer: a) 12/18+1/2-15/21 Merci c'est urgent

12/18 + 1/2 - 15/21
= 2/3 + 21/42 - 30/42
= 28/42 + 21/42 - 30/42
= 49/42 - 30/42
= 19/42

Salut :)

[tex]a) \frac{12}{18} + \frac{1}{2} - \frac{15}{21} \\ \\ \frac{12}{18} + \frac{1*9}{2*9} - \frac{15}{21} \\ \\ \frac{12}{18} + \frac{9}{18} - \frac{15}{21} \\ \\ \frac{21}{18} - \frac{15}{21} \\ \\ \frac{21:3}{18:3} - \frac{15:3}{21:3} \\ \\ \frac{7}{6} - \frac{5}{7} \\ \\ \frac{7*7}{6*7} - \frac{5*6}{7*6} \\ \\ \frac{49}{42} - \frac{30}{42} \\ \\ \frac{19}{42} [/tex]

J'espère t'avoir aidé(e) ! :)