Bonjour,
N.B. :
Diviser par une fraction revient à multiplier par son inverse.
a/b x c/d = a/d x c/b = (axc)/(bxd)
(-a) x (-b) = (-1) x (a) x (-1) x b = (-1) x (-1) x a x b = 1 x a x b = a x b
A = 2/3 : 4/9 = 2/3 x 9/4 = 4/2 x 9/3 = 2 x 3 = 6
B = 7/9 : 14 = 7/9 x 1/14 = 7/14 x 1/9 = 1/2 x 1/9 = 1/18
C = (-5)/6) : 15/(-12) = 5/6 : 15/12 = 5/6 x 12/15 = 5/15 x 12/6 = 1/3 x 2 = 2/3
D = (-5/10) : (-4/20) = 5/10 x 20/4 = 5 x 20/40 = 5/2
E = 4/3 + 6/5 : 2/10 = 4/3 + 6/5 x 10/2 = 4/3 + 6/2 x 10/5 = 4/3 + 6 = 4/3 + 18/3 = 22/3
F = (2/9 + 5/9) : (3/4 - 2/4) = 7/9 : 1/4 = 7/9 x 4 = 28/9
