Mathématiques

Question

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 :/

1 Réponse

  • 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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