Giúp em bài 4 với ạ.Em cảm ơn nhiều lắm ạ

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Giúp em bài 4 với ạ.Em cảm ơn nhiều lắm ạ
giup-em-bai-4-voi-a-em-cam-on-nhieu-lam-a

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Latifah 8 tháng 2020-11-01T16:35:16+00:00 1 Answers 49 views 0

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  1. Đáp án:

    $\begin{array}{l}
    a)\left( {x – 5} \right)\left( {x – 60} \right) = 0\\
     \Rightarrow \left[ \begin{array}{l}
    x – 5 = 0\\
    x – 60 = 0
    \end{array} \right.\\
     \Rightarrow \left[ \begin{array}{l}
    x = 5\\
    x = 60
    \end{array} \right.\\
    \text{Vậy}\,x = 5\,\text{hoặc}\,x = 60\\
    b)\left( {2x – 8} \right)\left( {5x – 155} \right) = 0\\
     \Rightarrow \left[ \begin{array}{l}
    2x – 8 = 0\\
    5x – 155 = 0
    \end{array} \right.\\
     \Rightarrow \left[ \begin{array}{l}
    x = 4\\
    x = 31
    \end{array} \right.\\
    \text{Vậy}\,x = 4\,\text{hoặc}\,x = 31\\
    c)\left( {132 – 4x} \right)\left( {x + 20} \right) = 0\\
     \Rightarrow \left[ \begin{array}{l}
    132 – 4x = 0\\
    x + 20 = 0
    \end{array} \right.\\
     \Rightarrow \left[ \begin{array}{l}
    x = 33\\
    x =  – 20
    \end{array} \right.\\
    \text{Vậy}\,x = 33\,\text{hoặc}\,x =  – 20\\
    d)\left( {275 – 11x} \right)\left( {x – 20} \right) + 6.7 = 42\\
     \Rightarrow \left( {275 – 11x} \right)\left( {x – 20} \right) = 0\\
     \Rightarrow \left[ \begin{array}{l}
    275 – 11x = 0\\
    x – 20 = 0
    \end{array} \right.\\
     \Rightarrow \left[ \begin{array}{l}
    x = 25\\
    x = 20
    \end{array} \right.\\
    \text{Vậy}\,x = 25\,\text{hoặc}\,x = 20\\
    e)\left( {x – 5} \right)\left( {9x – 27.3} \right) = 5.8 – 5.8\\
     \Rightarrow \left( {x – 5} \right)\left( {9x – 81} \right) = 0\\
     \Rightarrow \left[ \begin{array}{l}
    x – 5 = 0\\
    9x – 81 = 0
    \end{array} \right.\\
     \Rightarrow \left[ \begin{array}{l}
    x = 5\\
    x = 9
    \end{array} \right.\\
    \text{Vậy}\,x = 5\,\text{hoặc}\,x = 9\\
    f)\left( {6x – 4} \right)\left( {x + 2} \right) = 90 – 180:2\\
     \Rightarrow \left( {6x – 4} \right)\left( {x + 2} \right) = 0\\
     \Rightarrow \left[ \begin{array}{l}
    6x – 4 = 0\\
    x + 2 = 0
    \end{array} \right.\\
     \Rightarrow \left[ \begin{array}{l}
    x = \dfrac{4}{6} = \dfrac{2}{3}\\
    x =  – 2
    \end{array} \right.\\
    \text{Vậy}\,x = \dfrac{2}{3}\,\text{hoặc}\,x =  – 2
    \end{array}$

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