melih6752
résolu

Factoriser le premier membre de chaque équation, puis la résoudre.

a) 3x²+2x=0;

b) (x+2)(-x+1)+(x-3)(x+2)=0;

c) (2x-6)(-x+5)-2(-x+5)=0;

d) (5x-8)(x-3)-(x-1)(x-3)=0; 

aidez-moi svp :/

Répondre :

Aftershock
a) 3x²+2x = 0
x(3x+2) = 0
x = 0
ou
3x+2 = 0
3x = -2
x = -(2/3)

b) (x+2)(-x+1)+(x-3)(x+2) = 0
(x+2)((-x+1)+(x-3)) = 0
(x+2)(-4) = 0
x+2 = 0
x = -2

c) (2x-6)(-x+5)-2(-x+5) = 0
(-x+5)((2x-6)-2) = 0
(-x+5)(2x-8) = 0
-x+5 = 0
-x = -5
x = 5
ou
2x-8 = 0
2x = 8
x = 4

d) (5x-8)(x-3)-(x-1)(x-3) = 0
(x-3)((5x-8)-(x-1)) = 0
(x-3)(4x-7) = 0
x-3 = 0
x = 3
ou
4x-7 = 0
4x = 7
x = 7/4

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