Réponses

2014-04-08T22:53:47+02:00
Ex 1
* signifie multiplié par
3c*2a*(-a)*4d = 2*3*-1*4a²cd = 24a²cd

-15+7a+3-5a = -15+3+(7-5)a = 2a-12

10+3x-5-4x = 10-5+(3-4)x = 5-x

4y-4+x+6-5y-7x = (-7+1)x + (4-5)y -4+6 = -6x -y +4

Ex 2
la somme dex et de l'inverse de 3 : x+1/3
le produit de x et de 3 : x*3 = 3x
la somme de 6 et du double de x : 6+2x
le produit de 6 par la somme de x et de 3 : 6(x+3) = 6x+18

Ex 3
2(a+3) = 2a+2*3 = 2a+6
(2 - y)x5 = 2x5 -5y = 10-5y
-2x(3x-2) = -2x*3x+(-2x*-2) = -6x²+4x
(x-4)*3 = 3x-4*3 = 3x+12
10+3(x-5) = 10+3x-5*3 = 10-15+3x = 3x-5
4a - (4+3x) = 4a -4 -3a = 4a-3a-4 = a-4
4y - 3y (1 + 3y) = 4y-3y*1 -3y*3y = 4y -3y -9y² = -9y²+y
(2y+1)(3-4y) = 2y*3 + 2y*-4y +1*3 + 1*-4y = 6y-8y²+3-4y =-8y²+2y+3
4(5y-3)-(10y+1)(2y-4) = 4*5y+4*-3 - (10y*2y +10y*-4 + 2y -4) = 20y-12-(20y²+40y+2y-4) = 20y-12-20y²-42y+4 = -20y²-22y-8

ex4
A = 14x - 5x (4 - 2x)
1-
x = 2
A = 14*2 -5*2(4 - 2*2)
A = 28 -10(4-4)
A = 28 - 10*0
A = 28

x = -3
A = 14*-3 -5*-3(4 - 2*-3)
A = -42 + 15(4+6)
A = -42 + 15*10 = -42+150
A = 108

2
A = 14x - 5x (4 - 2x)
A = 14x -5x*4 -5x*-2x
A = 14x-20x +10x²
A = 10x²-6x