bonsoir
exercice 4
a/
(3x+4)(3x-4) = 3x*3x +3x*-4 +4*3x+4*-4 = 9x²-12x+12x-16 = 9x²-16
b/
x = 4/3
(3x+4)(3x-4) =(3*4/3 +4)(3*4/3 -4) = (4 +4)(4-4) =(8)(0) = 0
ou
9x²-16 = 9(4/3)² -16 = 9(16/9) -16 = 16-16 =0
exercice 5
a/
(6x+12) -5(x+2)
(6x+12) -5x-10
6x+12-5x-10
x +2
b/x =-5
x+2 =
-5+2 =
-3
exercice 6
a/
chosir un nbre 5
ajouter 3 5+3 = 8
multiplier par 4 8x4 = 32
soustraire le double du nbre de depart 32 -(5x2) =32-10 = 22
b/
chosir un nbre x
ajouter 3 x+3
multiplier par 4 4(x+3) = 4x+12
soustraire le double du nbre de depart 4x+12 -(2x) = 4x+12-2x = 2x+12
c/
2x+12 =0
2x = -12
x =-12/2
x = -6
