a) \(-1< \dfrac{5x}{13}< 0\)
\(\Rightarrow\left[{}\begin{matrix}\dfrac{5x}{13}>-1\\\dfrac{5x}{13}< 0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x>-\dfrac{13}{5}\\x< 0\end{matrix}\right.\)
Vậy \(x\in\left\{-\dfrac{13}{5},0\right\}\)
b) \(3\left(3x-\dfrac{1}{2}\right)^3+\dfrac{1}{9}=0\)
\(\Rightarrow3\left(3x-\dfrac{1}{2}\right)^3=-\dfrac{1}{9}\)
\(\Leftrightarrow\left(3x-\dfrac{1}{2}\right)^3=-\dfrac{1}{27}\)
\(\Leftrightarrow3x-\dfrac{1}{2}=-\dfrac{1}{3}\)
\(\Leftrightarrow3x=-\dfrac{1}{3}+\dfrac{1}{2}\)
\(\Leftrightarrow3x=\dfrac{1}{6}\)
\(\Rightarrow x=\dfrac{1}{18}\)
Vậy \(x=\dfrac{1}{18}\)
Xử câu b trc =)
b) \(3\left(3x-\dfrac{1}{2}\right)^3+\dfrac{1}{9}=0\)
\(\Leftrightarrow\left(3x-\dfrac{1}{2}\right)^3=-\dfrac{1}{9}:3=-\dfrac{1}{27}\)
\(\Leftrightarrow\left(3x-\dfrac{1}{2}\right)^3=\left(-\dfrac{1}{3}\right)^3\)
\(\Leftrightarrow3x-\dfrac{1}{2}=-\dfrac{1}{3}\)
\(\Leftrightarrow3x=-\dfrac{1}{3}+\dfrac{1}{2}=\dfrac{1}{6}\)
\(\Leftrightarrow x=\dfrac{1}{6}:3=\dfrac{1}{18}\)
a)\(\dfrac{-13}{13}< \dfrac{5x}{13}< \dfrac{0}{13}\)
=)-13<5x<0
=)5x=-10;-5
x=-1;-2