Réponse :
Explications étape par étape
Bonsoir
1)Développer
a) A=(4x-1)(x+5)
A = 4x * x + 4x * 5 - 1 * x - 1 * 5
A = 4x^2 + 20x - x - 5
A = 4x^2 + 19x - 5
b) B=3-2x(7x-3)
B = 3 - 2x * 7x - 2x * (-3)
B = 3 - 14x^2 + 6x
B = -14x^2 + 6x + 3
2)A=2 sur 7 + 1 sur 3 - 2.
A = 2/7 + 1/3 - 2
A = (2 x 3)/(7 x 3) + (1 x 7)/(3 x 7) - (2 x 21)/21
A = 6/21 + 7/21 - 42/21
A = 13/21 - 42/21
A = (-29/21)
B= 3 sur 4 - 2 sur 5 * 4.
B = 3/4 - 2/5 x 4
B = 3/4 - 8/5
B = (3 x 5)/(4 x 5) - (8 x 4)/(5 x 4)
B = 15/20 - 32/20
B = (-17/20)
