2 (2x-1) – 4x × (x-2)=-5 2 2 (5-2x) -(3x-2)=0 2 2 (2x-3)(4x +6x+9)-2x(2x+3)

0 bình luận về “2 (2x-1) – 4x × (x-2)=-5 2 2 (5-2x) -(3x-2)=0 2 2 (2x-3)(4x +6x+9)-2x(2x+3)”

1. Đáp án:

   $\begin{array}{l}
    + )\\
   {\left( {2x – 1} \right)^2} – 4x\left( {x – 2} \right) =  – 5\\
    \Rightarrow 4{x^2} – 4x + 1 – 4{x^2} + 8x + 5 = 0\\
    \Rightarrow 4x + 6 = 0\\
    \Rightarrow x =  – \dfrac{3}{2}\\
   Vay\,x =  – \dfrac{3}{2}\\
    + )\\
   {\left( {5 – 2x} \right)^2} – {\left( {3x – 2} \right)^2} = 0\\
    \Rightarrow \left( {5 – 2x + 3x – 2} \right)\left( {5 – 2x – 3x + 2} \right) = 0\\
    \Rightarrow \left( {x + 3} \right)\left( {7 – 5x} \right) = 0\\
    \Rightarrow \left[ \begin{array}{l}
   x + 3 = 0\\
   7 – 5x = 0
   \end{array} \right.\\
    \Rightarrow \left[ \begin{array}{l}
   x =  – 3\\
   x = \dfrac{7}{5}
   \end{array} \right.\\
   Vay\,x =  – 3\,hoac\,x = \dfrac{7}{5}\\
    + )\\
   \left( {2x – 3} \right)\left( {4{x^2} + 6x + 9} \right) – 2x{\left( {2x + 3} \right)^2} = 3\\
    \Rightarrow \left( {2x – 3} \right){\left( {2x + 3} \right)^2} – 2x{\left( {2x + 3} \right)^2} = 3\\
    \Rightarrow {\left( {2x + 3} \right)^2}.\left( {2x – 3 – 2x} \right) = 3\\
    \Rightarrow {\left( {2x + 3} \right)^2}.\left( { – 3} \right) = 3\\
    \Rightarrow {\left( {2x + 3} \right)^2} =  – 1\left( {vô\,nghiệm} \right)
   \end{array}$

   Vậy pt vô nghiệm.

   Bình luận