Réponse :
EXERCICE 1
1. Périmètre = Côté x 4
P = (2x + 3) x 4 = 8x + 12
2. x = 2,5
P = 8(2,5) + 12 = 20 + 12 = 32cm
3. P = (L + l) x 2
P = [(4x + 2) + 4] x 2 = (4x + 6) x 2 = 8x + 12
4. x = 2,5
P = 8(2,5) + 12 = 20 + 12 = 32
Vrai
EXERCICE 2
A = 1/6 + 2/3 - 5/9 = (1x3)/(6x3) + (2x6)/(3x6) - (5x2)/(9x2) = 3/18 +12/18 - 10/18 = 15/18 - 10/18 = 5/18
B = 2/5 - 3/10 + 1 = (2x2)/(5x2) - 3/10 + 10/10 = 4/10 - 3/10 + 10/10 = 14/10 - 3/10 = 11/10
Explications étape par étape
