\(\dfrac{1}{3}x+\dfrac{2}{5}\left(x+1\right)=0\)\(\Leftrightarrow\dfrac{1}{3}x+\dfrac{2}{5}x+\dfrac{2}{5}=0\)\(\Leftrightarrow\dfrac{11}{15}x=-\dfrac{2}{5}\)\(\Leftrightarrow x=-\dfrac{6}{11}\)Câu trả lời: \(\dfrac{1}{3}x+\dfrac{2}{5}\left(x+1\right)=0\)\(\Leftrightarrow\dfrac{1}{3}x+\dfrac{2}{5}x+\dfrac{2}{5}=0\)\(\Leftrightarrow\dfrac{11}{15}x=-\dfrac{2}{5}\)\(\Leftrightarrow x=-\dfrac{6}{11}\)