Réponse :
EXERCICE 1
A = 2/3 + 7/6 = (2*2)/(3*2) + 7/6 = 4/6 + 7/6 = 11/6
B = 4/15 + 4/5 = 4/15 + (4*3)/(5*3) = 4/15 + 12/15 = 16/15
C = 3/16 + 3/4 = 3/16 + (3*4)/(4*4) = 3/16 + 12/16 = 15/16
D = 3/4 - 1/2 = 3/4 - (1*2)/(2*2) = 3/4 - 2/4 = 1/4
E = 4/7 - 3/14 = (4*2)/(7*2) - 3/14 = 8/14 - 3/14 = 6/14 = (2*3)/(2*7) = 3/7
F = 7/27 - 1/9 = 7/27 - (1*3)/(9*3) = 7/27 - 3/27 = 4/27
G = 5/9 + 11/36 = (5*4)/(9*4) + 11/36 = 20/36 + 11/36 = 31/36
H = 11/42 + 9/7 = 11/42 + (9*6)/(7*6) = 11/42 + 54/42 = 65/42
I = 19/63 - 2/9 = 19/63 - (2*7)/(9*7) = 19/63 - 14/63 = 5/63
EXERCICE 2
A = 3/4 + 1/12 = (3*3)/(4*3) + 1/12 = 9/12 + 1/12 = 10/12 = (2*5)/(2*6) = 5/6
B = 7/15 + 1/3 = 7/15 + (1*5)/(3*5) = 7/15 + 5/15 = 12/15 = (3*4)/(3*5) = 4/5
C = 3/10 - 5/100 = (3*10)/(10*10) - 5/100 = 30/100 - 5/100 = 25/100 = (25*1)/(25*4) = 1/4
D = 17/6 - 1/2 = 17/6 - (1*3)/(2*3) = 17/6 - 3/6 = 14/6 = (2*7)/(2*3) = 7/3
Explications étape par étape :