a) 2x -2= 4 ( x -1) b) 3x(x -2)- 2x + 4=0 c) x+2/x-2 – 1/x= 2/ x^2 -2x |x – 3|= 3x +1 2x + 6/4 -2 <= x /3

0 bình luận về “a) 2x -2= 4 ( x -1) b) 3x(x -2)- 2x + 4=0 c) x+2/x-2 – 1/x= 2/ x^2 -2x |x – 3|= 3x +1 2x + 6/4 -2 <= x /3”

1. Đáp án:

    A)2x -2=4 ( x-1)

   ->2 x -2= 4 x-4

   ->2x-4x=-4+2

   ->-2x=-2

   ->x=1

   B)-> 3×2-6x-2x +4=0

   ->3×2-8x+4=0

   ->3×2-6x-2x+4=0

   ->(3×2-6x)-(2x-4)=0

   ->3x(x-2)-2(x-2)=0

   ->(x-2)(3x-2)=0 

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2. Đáp án:

   $\begin{array}{l}
   a)2x – 2 = 4\left( {x – 1} \right)\\
    \Rightarrow 2\left( {x – 1} \right) = 4\left( {x – 1} \right)\\
    \Rightarrow x = 1\\
   b)3x\left( {x – 2} \right) – 2x + 4 = 0\\
    \Rightarrow 3x\left( {x – 2} \right) – 2\left( {x – 2} \right) = 0\\
    \Rightarrow \left( {x – 2} \right)\left( {3x – 2} \right) = 0\\
    \Rightarrow \left[ \begin{array}{l}
   x – 2 = 0\\
   3x – 2 = 0
   \end{array} \right.\\
    \Rightarrow \left[ \begin{array}{l}
   x = 2\\
   x = \frac{2}{3}
   \end{array} \right.\\
   c)\frac{{x + 2}}{{x – 2}} – \frac{1}{x} = \frac{2}{{{x^2} – 2x}}\left( {dk:x \ne 0;x \ne 2} \right)\\
    \Rightarrow \frac{{x\left( {x + 2} \right) – x + 2}}{{x\left( {x – 2} \right)}} = \frac{2}{{x\left( {x – 2} \right)}}\\
    \Rightarrow {x^2} + 2x – x + 2 = 2\\
    \Rightarrow {x^2} + x = 0\\
    \Rightarrow x\left( {x + 1} \right) = 0\\
    \Rightarrow \left[ \begin{array}{l}
   x = 0\left( {ktm} \right)\\
   x =  – 1\left( {tm} \right)
   \end{array} \right.\\
   Vay\,x =  – 1\\
   d)\left| {x – 3} \right| = 3x + 1\left( {x \ge  – \frac{1}{3}} \right)\\
    \Rightarrow \left[ \begin{array}{l}
   x – 3 = 3x + 1\\
   x – 3 =  – 3x – 1
   \end{array} \right.\\
    \Rightarrow \left[ \begin{array}{l}
   x =  – 2\left( {ktm} \right)\\
   x = \frac{1}{2}\left( {tm} \right)
   \end{array} \right.\\
   Vay\,x = \frac{1}{2}\\
   e)\frac{{2x + 6}}{4} – 2 \le \frac{x}{3}\\
    \Rightarrow \frac{{x + 3}}{2} – 2 \le \frac{x}{3}\\
    \Rightarrow \frac{{x + 3 – 4}}{2} \le \frac{x}{3}\\
    \Rightarrow \frac{{x – 1}}{2} – \frac{x}{3} \le 0\\
    \Rightarrow \frac{{3x – 3 – 2x}}{6} \le 0\\
    \Rightarrow x – 3 \le 0\\
    \Rightarrow x \le 3
   \end{array}$

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