Réponse :
EX1.1
écrire sous la forme d'une fraction irréductible
A = 8/12 = 2 x 4/3 x 4 = 2/3
B = 1/3 + 1/2 rendre au même dénominateur
= 2/6 + 3/6 = 5/6
C = 2/3 + 5/6 = 4/6 + 5/6 = 9/6 = 3/2
D = 2/5) - 1 = 2/5 - 5/5 = 7/5
E = 5/4 - 7/6 = 15/12 - 14/12 = 1/12
F = 1/15 + 1/3 - 3/20 = 4/60 + 20/60 - 9/60 = 15/60 = 1/4
EX1.2
écrire sous la la forme d'une fraction, la plus simple possible
A = 1/a + 1/b = b/ab + a/ab = (a + b)/ab
B = 3/2a + 5/b = 3 b/2ab + 10 a/2ab = (3b + 10a)/2ab
C = 3/2a - 1/ab = 3b/2ab - 2/2ab = (3b - 2)/2ab
D = 1/2a + 1/6a + 1/15a = 15/30a + 5/30a + 2/30a = 22/30a = 11/15a
E = 1/a + 1/a² + 1/a³ = a²/a³ + a/a³ + 1/a³ = (a² + a + 1)/a³
F = 2/ab + 3/a² + 4/b² = 2ab/a²b² + 3b²/a²b² + 4a²/a²b²
= (a² + 2ab + b²)/a²b² = (a + b)²/a²b²
Explications étape par étape :