Exercice n°52 page 46 Consigne : Calculer sous forme fractionnaire et simplifier le résultat, si possible a) -5/8 - -7/24 - 1/6 = b) 4/5 + -2/3 + 9/10 – 5/6 = J

a = - 5 / 8 - ( - 7 / 24 ) - 1 / 6
= - 5 / 8 + 7 / 24 - 1 / 6
= - 15 / 24 + 7 / 24 - 4 / 24
= - 8 / 24 - 4 / 24
= - 12 / 24
= - 1 / 2

b = 4 / 5 + ( - 2 / 3 ) + 9 / 10 - 5 / 6
= 4 / 5 - 2 / 3 + 9 / 10 - 5 / 6
= 8 / 10 + 9 / 10 - 4 / 6 - 5 / 6
= 17 / 10 - 9 / 6
= 102 / 60 - 90 / 60
= 12 / 60
= 1 / 5

a) -5/8 - -7/24 - 1/6
= - 5 x 3 / 8 x 3 + 7/24 - 1 x 4 / 6 x 4
= - 15/24 + 7/24 - 4/24
= - 19/24 + 7/24
= - 12/24
= 12 x - 1 / 12 x 2
= - 1/2

b) 4/5 + -2/3 + 9/10 – 5/6
= 4/5 - 2/3 + 9/10 - 5/6
= 4 x 6 / 5 x 6 - 2 x 10 / 3 x 10 + 9 x 3 / 10 x 3 - 5 x 5 / 6 x 5
= 24/30 - 20/30 + 27/30 - 25/30
= 51/30 - 45/30
= 6/30
= 6 x 1 / 6 x 5
= 1/5