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

Toán Lớp 8: Giúp mik vs nhaaa! Thanks a) 3x – 5x(x – 1001) = 3003 b) (x + 2) (x − 1) − x + 1 = 0 c)($x^{2}$ − 11)(7 − 2x) − 4x = −14.

Toán Lớp 8: Giúp mik vs nhaaa! Thanks
a) 3x – 5x(x – 1001) = 3003
b) (x + 2) (x − 1) − x + 1 = 0
c)($x^{2}$ − 11)(7 − 2x) − 4x = −14.

Comments ( 2 )

  1. Giải đáp:
     
    Lời giải và giải thích chi tiết:
    a) $3x – 5x(x – 1001) = 3003$
    $3x – 5x² + 5005x = 3003$
    $3x – 5x² + 5005x – 3003 = 0$
    $5x² – 3x – 5005x + 3003 = 0$
    $x(5x – 3) – 1001(5x – 3) = 0$
    $(5x – 3)(x-1001) = 0$
    \(\left[ \begin{array}{l}x=\dfrac{3}{5}\\x=1001\end{array} \right.\) 
    b)$ (x + 2) (x − 1) − x + 1 = 0$
    $x² + x – 2 – x + 1 = 0$
    $x² – 1 = 0$
    $(x-1)(x+1) = 0$
    \(\left[ \begin{array}{l}x=1\\x=-1\end{array} \right.\) 
    c)
    $(x² – 11)(7-2x) – 4x = -14$
    $7x² – 2x³ – 77 + 22x – 4x + 14 = 0$
    $7x² – 2x³ + 18x – 63 = 0$
    $2x³ – 7x² – 18x + 63 = 0$
    $2x³ + 6x² – 13x² – 39x + 21x + 63 = 0$
    $(2x² – 13x + 21)(x+3) = 0$
    $(2x² – 6x – 7x + 21)(x+3) = 0$
    $(2x – 7)(x-3)(x+3) = 0$
    $\begin{cases} x = \dfrac{7}{2}\\x = 3\\x = -3 \end{cases}$

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

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