Tìm x :
\(\left(\dfrac{2}{3}x-\dfrac{4}{9}\right).\left(\dfrac{1}{2}+\dfrac{3}{7}:x\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}\left(\dfrac{2}{3}x-\dfrac{4}{9}\right)=0\\\left(\dfrac{1}{2}+\dfrac{3}{7}:x\right)=0\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}\dfrac{2}{3}x=\dfrac{4}{9}\\\dfrac{3}{7}:x=-\dfrac{1}{2}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\dfrac{2}{3}\\x=-\dfrac{6}{7}\end{matrix}\right.\)
Vậy.....
Tính :
\(\dfrac{1313}{1515}+\left(-\dfrac{1011}{5055}\right)=\dfrac{13}{15}-\dfrac{1}{5}=\dfrac{2}{3}\)