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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: Tìm x a) x(2x + 3) – 2x^2 = 9 b) (2x – 3)^2 + 3x(3 – 2x) = 0 c) (x + 3)^2 – 4x^2 = 0

Toán Lớp 8: Tìm x
a) x(2x + 3) – 2x^2 = 9
b) (2x – 3)^2 + 3x(3 – 2x) = 0
c) (x + 3)^2 – 4x^2 = 0

Comments ( 1 )

  1. $#Blue$ gửi
    Giải đáp và Lời giải và giải thích chi tiết:
     a) 
    x(2x + 3) – 2x² = 9
    2x² + 3x – 2x² = 9
    ⇔ 3x = 9
    ⇒ x = 9 : 3 = 3
    b)
    (2x – 3)² + 3x(3 – 2x) = 0
    ⇔ (3-2x)² + 3x(3-2x) = 0
    (3-2x)(3-2x+3x) = 0
    (3-2x)(3+x) = 0
    $\left \{ {{3-2x=0} \atop {3+x=0}} \right.$ ⇔ $\left \{ {{x=3/2} \atop {x=(-3)}} \right.$ 
    c)
    (x + 3)² – 4x² = 0
    ⇔ (x + 3)² – (2x)² = 0
    (x+3-2x)(x+3+2x) = 0
    (3-x)(3x+3) = 0
    $\left \{ {{3-x=0} \atop {3x+3=0}} \right.$ ⇔ $\left \{ {{x=3} \atop {x=(-1)}} \right.$ 

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222-9+11+12:2*14+14 = ? ( )

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