Bonjour
73)
a. 5/12 - 5/3 + 1/6 - 2/9
= (5 x 3) / (12 x 3) - (5 x 12) / (3 x 12) + (1 x 6) / (9 x 6) - (2 x 4) / (9 x 4)
= 15/36 - 60/36 + 6/36 - 8/36
= - 47/36
b. 3/7 + 3/4 - 5/2 - 17/8
= (3 x 8) / (7 x 8) + (3 x 14) / (4 x 14) - (5 x 28) / (2 x 28) - (17 x 7) / (8 x 7)
= 24/56 + 42/56 - 140/56 - 119/56
= - 193/56
74)
a. 2 - 1/3 + 1/6 - 1/9
= (2 x 18) / (1 x 18) - (1 x 6) / (3 x 6) + (1 x 3) / (6 x 3) - (1 x 2) / (9 x 2)
= 36/18 - 6/18 + 3/18 - 2/18
= 31/18
b. 1 + 1/2 + 3/4 + 5/6
= (1 x 12) / (1 x 12) + (1 x 6) / (2 x 6) + (3 x 3) / (4 x 3) + (5 x 2) / (6 x 2)
= 12/12 + 9/12 + 10/12
= 31/12.
