Question

Bài 1:

a) \(\dfrac{1}{2}\)<\(\dfrac{...}{9}\)<\(\dfrac{...}{18}< \dfrac{2}{3}\)

b) \(\dfrac{-1}{2}< \dfrac{...}{15}< \dfrac{...}{30}< \dfrac{-2}{5}\)

 

 

Answer 1

a) \(\dfrac{1}{2}< \dfrac{x}{9}< \dfrac{y}{18}< \dfrac{2}{3}\)

\(\Leftrightarrow\dfrac{9}{18}< \dfrac{2x}{18}< \dfrac{y}{18}< \dfrac{12}{18}\)

\(\Leftrightarrow\left\{{}\begin{matrix}2x=10\\y=11\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=5\\y=11\end{matrix}\right.\)

b) \(\dfrac{-1}{2}< \dfrac{x}{15}< \dfrac{y}{30}< \dfrac{-2}{5}\)

\(\Leftrightarrow\dfrac{-15}{30}< \dfrac{2x}{30}< \dfrac{y}{30}< \dfrac{-12}{30}\)

\(\Leftrightarrow\left\{{}\begin{matrix}2x=-14\\y=-13\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-7\\y=-13\end{matrix}\right.\)