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

Toán Lớp 8: a) x2- 25 – ( x+5 ) = 0 b) 3x(x-2) – x+ 2 = 0 c) 3x (x + 5) – 3x – 15=0 d) ( 2x – 1) 2 – 25 =0 e) x2 (x – 3) + 12 – 4x = 0 f) .(2x -1)2

Tháng Chín 2, 2022 Toán học 1 Comment 0 views

Toán Lớp 8: a) x2- 25 – ( x+5 ) = 0
b) 3x(x-2) – x+ 2 = 0
c) 3x (x + 5) – 3x – 15=0
d) ( 2x – 1) 2 – 25 =0
e) x2 (x – 3) + 12 – 4x = 0 f) .(2x -1)2- (4×2 – 1) = 0
g) ( 2x -1)2 – ( x -3)2=0
h) x2 + 36 = 12x
i) 2×2 + 3x – 5 = 0
j) x(x+1)(x+6) – x3 = 5x

Comments ( 1 )

  1. ngocbichchau
    ngocbichchau
    2 Tháng Chín, 2022 at 5:31 sáng
    Reply
    Giải đáp +Lời giải và giải thích chi tiết:
    $a) x² – 25 – ( x + 5 ) = 0 $
    $⇔ ( x – 5 )( x + 5 ) – ( x + 5 ) = 0 $
    $⇔ ( x + 5 )( x – 6 ) = 0 $
    ⇔$\left[\begin{matrix} x+ 5 = 0 \\ x- 6 = 0 \end{matrix}\right.$
    ⇔$\left[\begin{matrix} x = -5 \\ x = 6 \end{matrix}\right.$
    $b) 3x( x – 2 ) – x + 2 = 0 $
    $⇔ ( 3x – 1 )( x – 2 ) = 0 $
    ⇔ $\left[\begin{matrix} 3x – 1 = 0\\ x – 2 = 0 \end{matrix}\right.$
    ⇔ $\left[\begin{matrix} x = \dfrac{1}{3} \\ x = 2 \end{matrix}\right.$
    $c) 3x( x + 5 ) – 3x – 15 = 0 $
    $⇔ 3x( x + 5 ) -3( x + 5 ) = 0 $
    $⇔ 3( x – 1 )( x + 5 ) = 0 $
    ⇔ $\left[\begin{matrix} x =1\\ x = -5\end{matrix}\right.$
     $d) ( 2x – 1 )² – 25 = 0 $
    $⇔ ( 2x – 1 – 5 )( 2x – 1 + 5 ) = 0 $
    ⇔ $\left[\begin{matrix} 2x – 6 = 0 \\ 2x + 4 = 0 \end{matrix}\right.$
    ⇔ $\left[\begin{matrix} x = 3 \\ x = -2 \end{matrix}\right.$
    $e) x²( x – 3 ) + 12 – 4x = 0 $
    $⇔ x²( x – 3 ) – 4( x – 3 ) = 0 $
    $⇔ ( x – 3 )( x + 2 )( x – 2 ) = 0 $
    ⇔ $\left[\begin{matrix} x = 3\\ x = ±2 \end{matrix}\right.$
    $f) ( 2x – 1 )² – ( 4x² – 1 ) = 0 $
    $⇔ ( 2x – 1 )( 2x – 1 – 2x – 1 ) = 0 $
    $⇔ ( 2x – 1 ). (-2) = 0 $
    $⇔ 2x = 1 $
    $⇔ x = \dfrac{1}{2} $
    $g) ( 2x – 1 )² – ( x – 3 )² = 0 $
    $⇔ ( 2x – 1 + x – 3 )( 2x – 1 – x + 3 ) = 0 $
    $⇔ ( 3x – 4 )( x + 2 ) = 0 $
    ⇔ $\left[\begin{matrix} x = \dfrac{4}{3} \\ x = -2 \end{matrix}\right.$
    $h) x² + 36 = 12x $
    $⇔ x² – 12x + 36 = 0 $
    $⇔ ( x – 6 )² = 0 $
    $⇔ x – 6 = 0 $
    $⇔ x = 6 $
    $i) 2x² + 3x – 5 = 0 $
    $⇔ 2x² – 2x + 5x – 5 = 0 $
    $⇔ 2x( x – 1 ) +5( x – 1 ) = 0 $
    $⇔ ( 2x + 5 )( x – 1 ) = 0 $
    ⇔ $\left[\begin{matrix} x = \dfrac{-5}{2} \\ x =1\end{matrix}\right.$
    $j) x( x + 1 )( x + 6 ) – x³ = 5x $
    $⇔ x( x² + 7x + 6 ) – x³ – 5x = 0 $
    $⇔ x³ + 7x² + 6x – x³ – 5x = 0 $
    $⇔ 7x² + x = 0 $
    $⇔ x( 7x + 1 ) = 0 $
    ⇔ $\left[\begin{matrix} x = 0 \\ x = \dfrac{-1}{7} \end{matrix}\right.$

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

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