làm câu b nha! Question làm câu b nha! in progress 0 Môn Toán Phúc Điền 5 years 2021-05-23T20:38:13+00:00 2021-05-23T20:38:13+00:00 1 Answers 150 views 0
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$b)\dfrac{2-x}{2013}-1=\dfrac{1-x}{2014}-\dfrac{x}{2015}\\ \Leftrightarrow \dfrac{2-x}{2013}=\dfrac{1-x}{2014}-\dfrac{x}{2015}+1\\ \Leftrightarrow \dfrac{2-x}{2013}+1=\dfrac{1-x}{2014}+1+1-\dfrac{x}{2015}\\ \Leftrightarrow \dfrac{2015-x}{2013}=\dfrac{2015-x}{2014}+\dfrac{2015-x}{2015}\\ \Leftrightarrow (2015-x)\left(\dfrac{1}{2013}-\dfrac{1}{2014}-\dfrac{1}{2015}\right)=0\\ \Leftrightarrow x=2015$