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

Toán Lớp 8: Tìm x a) (x+3)(x+4)-(x-3)(x-5)=2

Toán Lớp 8: Tìm x a) (x+3)(x+4)-(x-3)(x-5)=2

Comments ( 2 )

  1. $\text{( x + 3 )( x + 4 ) – ( x – 3 )( x – 5 ) = 2}$
    $\text{⇔ $x^{2}$ + 4x + 3x + 12 – ( $x^{2}$ – 5x – 3x + 15 ) = 2}$
    $\text{⇔ $x^{2}$ + 4x + 3x + 12 – ( $x^{2}$ – 8x + 15 ) = 2}$ 
    $\text{⇔ $x^{2}$ + 4x + 3x + 12 – $x^{2}$ + 8x – 15 = 2}$
    $\text{⇔ 15x + 12 – 15 = 2}$
    $\text{⇔ 15x – 3 = 2}$
    $\text{⇔ 15x = 5}$
    $\text{⇔ x = }$ $\dfrac{1}{3}$
    Vậy $\text{x = }$ $\dfrac{1}{3}$

  2. Giải đáp+Lời giải và giải thích chi tiết:
     (x+3).(x+4)-(x-3).(x-5)=2
    ⇔ x²+7x+12-x²+8x-15=2
    ⇔ 15x-3=2
    ⇔ 15x=5
    ⇔ x=1/3
    Vậy x=1/3
    @Festivals

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