Calcule les expressions suivants en donnant le résultat sous forme d'une fraction irréductible :

A = 7/3 - 2/3 x 11/8 = ?

B = 2/45 : 6/5 + 7/9 = ?

C = (1/3+5/12) x (1/3 - 5/9) = ?

D = 5/7 + 1/7 / 2 - 9/14 = ?

Merci d'avance !

1
A = 7/3 - 2/3 x 11/8 = ?B = 2/45 : 6/5 + 7/9 = ?



C = (1/3+5/12) x (1/3 - 5/9) = ?



D = 5/7 + 1/7 / 2 - 9/14 = ?
A = 7/3 - 2/3 x 11/8 = ?B = 2/45 : 6/5 + 7/9 =

C = (1/3+5/12) x (1/3 - 5/9) = ?

D = 5/7 + 1/7 / 2 - 9/14 = ?
A = 5/3 x 11/8 = 55/24
55/24 est simplifié au max ?
A = 7/3 - 22/ 24 = 56/24 - 22/24 = 24/24 = 1/1 = 1 B = 2/45 x 5/6 + 7/9 = 10/270 + 7/9 = 10/270 + 210/270 = 220/270 = 22/27 C= (1/3 + 5/12) x (1/3 - 5/9) = (4/12 + 5/12) x (3/9 - 5/9) = 9/12 x -2/9 = 18/108 = 1/6 D = 6/7 / 28/14 - 9/14 = 6/7 / 19/14 = 6/7 x 14/19 = 84/133

Réponses

2013-09-19T19:30:14+02:00
A = 7/3 - (2x8)/(11x3) = (11x7)/(11x3) - 16/(11x3) = (77+16)/33 = 93/33 = 31/11
B = (2x5)/(6x45) +7/9 = 2/(6x9) +7/9 car 45 = 9x5 on simplifie les 5
B = 2/54 + 7x6/(9x6) = 2/54 + 42/54 = 44/54 = 22/27
C = (4/(4x3)+5/12) x ( 3/9-5/9) = 9/12 x -2/9 = 3/4 - 2/9 = (3x9)/(4x9) - (2x4)/(4x9) 
C = 27-8/36 = 19/36
D = 5x2/14 + 2/14 -9/14 = (10+2-9)/14 = 3/14
Erreur dans le D j'ai oublié que c'était 1/7/2 = 1/14 donc on obtient 2/14 = 1/7