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

Toán Lớp 8: Tìm x a) 7x^2 + 2x=0 b) x (x+4)- x^2- 6x= 10 c) x( x-1) + 2x-2= 0 d) (3x-1)^2 – (x+5)^2= 0

Toán Lớp 8: Tìm x
a) 7x^2 + 2x=0
b) x (x+4)- x^2- 6x= 10
c) x( x-1) + 2x-2= 0
d) (3x-1)^2 – (x+5)^2= 0

Comments ( 2 )

  1. $\text{Giải đáp+Lời giải và giải thích chi tiết:}$
    $a,  7x^2+2x=0$
    $⇔x(7x+2)=0$
    $⇔\left[ \begin{array}{l}x=0\\7x+2=0\end{array} \right.$
    $⇔\left[ \begin{array}{l}x=0\\x=\dfrac{-2}{7}\end{array} \right.$
    $\text{Vậy x=0 hoặc x=$\dfrac{-2}{7}$}$
    $b, x(x+4)-x^2-6x=10$
    $⇔x^2+4x-x^2-6x=10$
    $⇔-2x=10$
    $⇔ x=-5$
    $\text{Vậy x=-5}$
    $c, x(x-1)+2x-2=0$
    $⇔x(x-1)+2(x-1)=0$
    $⇔(x-1)(x+2)=0$
    $⇔\left[ \begin{array}{l}x-1=0\\x+2=0\end{array} \right.$
    $⇔\left[ \begin{array}{l}x=1\\x=-2\end{array} \right.$
    $\text{Vậy x=1 hoặc x=-2}$
    $d,(3x-1)^2-(x+5)^2=0$
    $⇔(3x-1-x-5)(3x-1+x+5)=0$
    $⇔(2x-6)(4x+4)=0$
    $⇔\left[ \begin{array}{l}2x-6=0\\4x+4=0\end{array} \right.$
    $⇔\left[ \begin{array}{l}x=3\\x=-1\end{array} \right.$
    $\text{Vậy x=3 hoặc x=-1}$

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

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