Question

a) x/14 - 1/7 = -3/4

b) x -1/8 =5/8

c) 1/5 + 1/11 < x/55 < 2/5 + 1/55 mà x thuộc z

 

Answer 1

a) Ta có: \(\dfrac{x}{14}-\dfrac{1}{7}=\dfrac{-3}{4}\)

\(\Leftrightarrow\dfrac{x}{14}=\dfrac{-3}{4}+\dfrac{1}{7}=\dfrac{-21}{28}+\dfrac{4}{28}=\dfrac{-17}{28}\)

hay \(x=\dfrac{-17\cdot14}{28}=\dfrac{-17}{2}\)

Vậy: \(x=-\dfrac{17}{2}\)

Answer 2

\(a)\dfrac{x}{14}-\dfrac{1}{7}=\dfrac{-3}{4}\)

\(\dfrac{x}{14}=\dfrac{-3}{4}+\dfrac{1}{7}\)

\(\dfrac{x}{14}= \dfrac{-17}{28}\)

\(x=\dfrac{14.(-17)}{28}\)

\(x=\dfrac{-17}{2}\)

\(b)x-\dfrac{1}{8}=\dfrac{5}{8}\)

\(x=\dfrac{5}{8}+\dfrac{1}{8}\)

\(x=\dfrac{6}{8}=\dfrac{3}{4}\)

\(c)\dfrac{1}{5}+\dfrac{1}{11}<\dfrac{x}{55}<\dfrac{2}{5}+\dfrac{1}{55}(x​​thuộc Z )\)

\(\Rightarrow \dfrac{11}{55}+\dfrac{5}{55}<\dfrac{x}{55}<\dfrac{22}{55}+\dfrac{1}{55} \)

\(\Rightarrow \dfrac{16}{55}<\dfrac{x}{55}<\dfrac{23}{55}\)

\(\Rightarrow 21< x < 23\)

\(\Rightarrow x=22\)