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Kết quả phép tính trên đâu mà bảo mình hộ bạn
`Answer:`
\(\frac{x+721}{2020}+\frac{x+21}{700}+\frac{x+721}{2021}=-1\) (Mình bổ sung đề nhé.)
\(\Leftrightarrow\frac{x+721}{2020}+[\frac{x+21}{700}+1]+\frac{x+721}{2021}=0\)
\(\Leftrightarrow\frac{x+721}{2020}+\frac{x+721}{700}+\frac{x+721}{2021}=0\)
\(\Leftrightarrow\left(x+721\right).\left(\frac{1}{2020}+\frac{1}{700}+\frac{1}{2021}\right)=0\)
Mà \(\frac{1}{2020}+\frac{1}{700}+\frac{1}{2021}\ne0\)
\(\Rightarrow x+721=0\Leftrightarrow x=-721\)
