Tìm x: a/ 1/15 – x = 3/10 b/ 5/12 + 5/x -1/8=1/2 c/ 4/10 – x = -3/20 + 3/5

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1. Đáp án:

    

   Giải thích các bước giải:

   a) $\frac{1}{15}$ – x = $\frac{3}{10}$

   => x= $\frac{1}{15}$ – $\frac{3}{10}$

   => x = $\frac{-7}{30}$

   Vậy x =$\frac{-7}{30}$

   b)$\frac{5}{12}$ + $\frac{5}{x}$ – $\frac{1}{8}$ = $\frac{1}{2}$

   => $\frac{5}{12}$ + $\frac{5}{x}$ = $\frac{1}{2}$ + $\frac{1}{8}$

   => $\frac{5}{12}$ + $\frac{5}{x}$ = $\frac{5}{8}$

   => $\frac{5}{x}$ = $\frac{5}{12}$ – $\frac{5}{8}$

   => $\frac{5}{x}$ = $\frac{-5}{24}$

   => -5x = 5 . 24

   => -5x = 100

   => x = 20

   Vậy x = 20

   c) $\frac{4}{10}$ – x = $\frac{-3}{20}$ + $\frac{3}{5}$

   => $\frac{4}{10}$ – x = $\frac{9}{20}$

   => x = $\frac{4}{10}$ – $\frac{9}{20}$

   => x = $\frac{-1}{20}$

   Vậy x = $\frac{-1}{20}$ 

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2. `a, 1/15 -x=3/10`

   `x=1/15 – 3/10`

   `x=2/30 – 9/30`

   `x=(-7)/30`

   `b,5/12 + 5/x -1/8 =1/2`

   `5/12 + 5/x=1/2+1/8`

   `5/12 + 5/x=4/8+1/8`

   `5/12 + 5/x=5/8`

   `5/x=5/8 – 5/12`

   `5/x=15/24 – 10/24`

   `5/x =5/24`

   `=>x=24`

   `c, 4/10 – x=(-3)/20 + 3/5`

   `4/10 -x=(-3)/20 + 12/20`

   `4/10 -x=9/20`

   `x=4/10 – 9/20`

   `x=8/20 – 9/20`

   `x=(-1)/20`

   ~ Học tốt ~

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