Câu 1 : Tìm x , biết : a,( x-5/8 ). 5/18 = 15 / 36 b, | x- 1/3 | = 5/6

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1. a) $(x-\dfrac{5}{8}).$ $\dfrac{5}{18}$ $=$ $\dfrac{15}{36}$ 

       $(x-\dfrac{5}{8})$ $=$ $\dfrac{15}{36}$ $.$ $\dfrac{18}{5}$ 

       $x-\dfrac{5}{8}$ $=$ $\dfrac{3}{2}$

   ⇒ $x=\dfrac{3}{2}$ $+$ $\dfrac{5}{8}$ $=$ $\dfrac{12}{8}$ $+$ $\dfrac{5}{8}$ $=$ $\dfrac{17}{8}$

   b) $|x-\dfrac{1}{3}|$ $=$ $\dfrac{5}{6}$

       $|x-\dfrac{2}{6}|$ $=$ $\dfrac{5}{6}$

   ⇒ TH1: $x-\dfrac{2}{6}$ $=$ $\dfrac{5}{6}$ ⇒ $x=\dfrac{5}{6}$ $+$ $\dfrac{2}{6}$ $=$ $\dfrac{7}{6}$

   ⇒ TH2: $x-\dfrac{2}{6}$ $=$ $-\dfrac{5}{6}$ ⇒ $x=-\dfrac{5}{6}$ $+$ $\dfrac{2}{6}$ $=$ $\dfrac{-1}{2}$ 

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2. Đáp án:

   a, (x – $\frac{5}{8}$) . $\frac{5}{18}$ = $\frac{15}{36}$

   x – $\frac{5}{8}$ = $\frac{15}{36}$ : $\frac{5}{18}$

   x – $\frac{5}{8}$ = $\frac{3}{2}$ 

              x = $\frac{3}{2}$ + $\frac{5}{8}$

              x = $\frac{17}{8}$

    Vậy x = $\frac{17}{8}$

   b, |x – $\frac{1}{3}$| = $\frac{5}{6}$

   ⇒ Có 2 trường hợp

   TH1: x – $\frac{1}{3}$ = $\frac{5}{6}$

                x = $\frac{5}{6}$ + $\frac{1}{3}$

                x = $\frac{7}{6}$

   TH2: x – $\frac{1}{3}$ = -$\frac{5}{6}$

              x = -$\frac{5}{6}$ + $\frac{1}{3}$

              x = -$\frac{1}{2}$

   Vậy x = $\frac{7}{6}$ hoặc -$\frac{1}{2}$

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