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

Toán Lớp 8: Bài 1 a,x(x+2)-x^2+3x=4 b,6x(x-12)-2x+24=0 Giúp mình với mọi người

Toán Lớp 8: Bài 1
a,x(x+2)-x^2+3x=4
b,6x(x-12)-2x+24=0
Giúp mình với mọi người

Comments ( 2 )

  1. a) x(x+2) – x²+3x = 4
    <=> x(x+2) – x(x+3) = 4
    <=> (x+2)(x+3) = 4
               x+2 = 4
    <= > [
              x+3 = 4
                x = 2
    <=> [
               x = 1
    b) 6x(x-12) – 2x + 24 = 0
    <=> 6x(x-12) – 2(x-12) = 0
    <=> (x-12)(6x – 2) = 0
              x-12 = 0
    <=> [
              6x – 2 = 0
                x= 12
    <=> [
              6x = 2 
                x = 12
    <=> [
                x = 1/3

  2. a, x(x+2) – x^2 + 3x =4
    x^2 + 2x – x^2 + 3x =4
    5x =4
    => x= 4/5
    b, 6x(x-12) – 2x +24 =0
    6x(x-12) – 2( x -12)=0
    (x-12)(6x-2)=0
    =>\(\left[ \begin{array}{l}x-12=0\\6x-2=0\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=12\\6x=2\end{array} \right.\) 
    =>\(\left[ \begin{array}{l}x=12\\x=\frac{1}{3}\end{array} \right.\)
    \text{Vậy} x ∈ { 1/3 ; 12}

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

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