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

Toán Lớp 8: Tìm x, biết a) 3(x+5) – x2-5x = 0 b) x3 – 4×2 +4x = 0 c) x2 – 7x +12 = 0 d) (x-2)(3x-4) – x2 +4 = 0 e) (3x-3)2-(x+5)2= 0

Home/ Toán Lớp 8: Tìm x, biết a) 3(x+5) – x2-5x = 0 b) x3 – 4×2 +4x = 0 c) x2 – 7x +12 = 0 d) (x-2)(3x-4) – x2 +4 = 0 e) (3x-3)2-(x+5)2= 0

Toán Lớp 8: Tìm x, biết a) 3(x+5) – x2-5x = 0 b) x3 – 4×2 +4x = 0 c) x2 – 7x +12 = 0 d) (x-2)(3x-4) – x2 +4 = 0 e) (3x-3)2-(x+5)2= 0

Tháng Năm 22, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: Tìm x, biết
a) 3(x+5) – x2-5x = 0
b) x3 – 4×2 +4x = 0
c) x2 – 7x +12 = 0
d) (x-2)(3x-4) – x2 +4 = 0
e) (3x-3)2-(x+5)2= 0

Comments ( 2 )

  1. dinhcongson
    dinhcongson
    22 Tháng Năm, 2022 at 5:03 sáng
    Reply
    $\text{a) 3( x + 5 ) – x² – 5x = 0 }$
    $\text{⇔ 3( x + 5 ) -x( x + 5 ) = 0 }$
    $\text{⇔ ( 3 -x )( x + 5 ) = 0 }$
    ⇔$\left[\begin{matrix} 3 -x = 0\\ x + 5  =0 \end{matrix}\right.$
    ⇔ $\left[\begin{matrix} x = 3\\ x = -5 \end{matrix}\right.$
    $\text{b) x³ – 4x² + 4x = 0 }$
    $\text{⇔ x( x² – 4x + 4 ) = 0 }$
    $\text{⇔x( x – 2 )² = 0}$
    ⇔$\left[\begin{matrix} x= 0\\ x=2\end{matrix}\right.$
    $\text{c) x² – 7x + 12 = 0 }$
    $\text{⇔ x² – 3x – 4x + 12 = 0 }$
    $\text{⇔ x( x – 3 ) -4( x – 3 ) = 0}$
    $\text{⇔ ( x – 4 )( x – 3 ) = 0}$
    ⇔ $\left[\begin{matrix} x = 4 \\ x = 3 \end{matrix}\right.$
    $\text{d) ( x – 2 )( 3x – 4 ) – x² + 4 = 0 }$
    $\text{⇔ ( x – 2 )( 3x – 4 ) – ( x + 2 )( x – 2 ) = 0}$
    $\text{⇔ ( x – 2 )( 3x – 4 – x – 2 ) = 0 }$
    $\text{⇔ ( x – 2 )( 2x – 6 ) = 0 }$
    $\text{⇔ ( x – 2 )( x – 3 ).2 = 0 }$
    ⇔ $\left[\begin{matrix} x = 2\\ x = 3\end{matrix}\right.$
    $\text{e) ( 3x – 2 ).2 – ( x + 5 ).2 = 0 }$
    $\text{⇔ 2.( 3x – 2 – x – 5 ) = 0 }$
    $\text{⇔ 2.( 2x – 10 ) = 0}$
    $\text{⇔ 4.( x – 5 ) = 0}$
    $\text{⇔ x – 5 = 0 }$
    $\text{⇔ x = 5 }$

  2. diemmyhoa
    diemmyhoa
    22 Tháng Năm, 2022 at 5:03 sáng
    Reply
    Giải đáp + giải thích :

    toan-lop-8-tim-biet-a-3-5-2-5-0-b-3-42-4-0-c-2-7-12-0-d-2-3-4-2-4-0-e-3-3-2-5-2-0

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

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