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

Toán Lớp 8: `( x – 4)^2 – 36 = 0` `4x ^3 = 9x `

Toán Lớp 8: ( x – 4)^2 – 36 = 0
4x ^3 = 9x

Comments ( 2 )

  1. Giải đáp:
     
    Lời giải và giải thích chi tiết:
    (x-4)^2-36=0
    <=>(x-4)^2=36
    <=>(x-4)^2=(+-6)^2
    $⇔\left[\begin{matrix} x-4=6\\ x-4=-6\end{matrix}\right.$
    $⇔\left[\begin{matrix} x=10\\ x=-2\end{matrix}\right.$
    Vậy S={10;-2}
    _______________________________________
    4x^3=9x
    <=>4x^3-9x=0
    <=>x(4x^2-9)=0
    $⇔\left[\begin{matrix}x=0\\4x^2-9=0\end{matrix}\right.$
    $⇔\left[\begin{matrix}x=0\\4x^2=9\end{matrix}\right.$
    $⇔\left[\begin{matrix}x=0\\x^2=\dfrac{9}{4}\end{matrix}\right.$
    $⇔\left[\begin{matrix}x=0\\x=±\dfrac{3}{2}\end{matrix}\right.$
    Vậy S={0;3/2;-3/2}
    #Devil

  2. (x-4)^2 – 36=0
    <=> (x-4)^2 – 6^2 =0
    <=> (x-4-6)(x-4+6)=0
    <=> (x-10)(x+2)=0
    <=> \(\left[ \begin{array}{l}x-10=0\\x+2=0\end{array} \right.\) 
    <=> \(\left[ \begin{array}{l}x=10\\x=-2\end{array} \right.\) 
    Vậy x in { 10 ;-2}
    4x^3 = 9x
    <=> 4x^3 – 9x=0
    <=> x(4x^2  -9)=0
    <=> x[(2x)^2 -3^2]=0
    <=> x(2x-3)(2x+3)=0
    <=>\(\left[ \begin{array}{l}x=0\\2x-3=0\\2x+3=0\end{array} \right.\) 
    <=> \(\left[ \begin{array}{l}x=0\\x=\dfrac{3}{2}\\x= \dfrac{-3}{2}\end{array} \right.\) 
    Vậy x in{ 0 ; 3/2 ; -3/2} 
     

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

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