Câu hỏi của Hồ Ngọc Ánh

\(\dfrac{5}{14}.\dfrac{7}{10}=\dfrac{1}{4}\)\(-\dfrac{1}{4}+\dfrac{5}{4}=\dfrac{4}{4}=1\)\(\dfrac{15}{17}:\dfrac{25}{34}=\dfrac{15}{17}.\dfrac{34}{25}=\dfrac{6}{5}\)\(\dfrac{4}{5}-\dfrac{3}{-5}=\dfrac{4}{5}+\dfrac{3}{5}=\dfrac{7}{5}\)\(\dfrac{8}{15}.\dfrac{30}{12}=\dfrac{4}{3}\)\(-\dfrac{1}{3}+\dfrac{5}{2}=\dfrac{-2}{6}+\dfrac{15}{6}=\dfrac{13}{6}\)\(-\dfrac{5}{7}.\dfrac{21}{-10}=\dfrac{3}{2}\)\(\dfrac{5}{-3}+\dfrac{-7}{6}=\dfrac{-10}{6}+\dfrac{-7}{6}=\dfrac{-17}{6}\)\(-\dfrac{24}{25}:\left(\dfrac{-10}{25}\right)=-\dfrac{24}{25}.\dfrac{25}{-10}=\dfrac{12}{5}\)\(-\dfrac{6}{15}-\dfrac{3}{10}=\dfrac{-12}{30}-\dfrac{9}{30}=-\dfrac{21}{30}\)Câu trả lời: \(\dfrac{5}{14}.\dfrac{7}{10}=\dfrac{1}{4}\)\(-\dfrac{1}{4}+\dfrac{5}{4}=\dfrac{4}{4}=1\)\(\dfrac{15}{17}:\dfrac{25}{34}=\dfrac{15}{17}.\dfrac{34}{25}=\dfrac{6}{5}\)\(\dfrac{4}{5}-\dfrac{3}{-5}=\dfrac{4}{5}+\dfrac{3}{5}=\dfrac{7}{5}\)\(\dfrac{8}{15}.\dfrac{30}{12}=\dfrac{4}{3}\)\(-\dfrac{1}{3}+\dfrac{5}{2}=\dfrac{-2}{6}+\dfrac{15}{6}=\dfrac{13}{6}\)\(-\dfrac{5}{7}.\dfrac{21}{-10}=\dfrac{3}{2}\)\(\dfrac{5}{-3}+\dfrac{-7}{6}=\dfrac{-10}{6}+\dfrac{-7}{6}=\dfrac{-17}{6}\)\(-\dfrac{24}{25}:\left(\dfrac{-10}{25}\right)=-\dfrac{24}{25}.\dfrac{25}{-10}=\dfrac{12}{5}\)\(-\dfrac{6}{15}-\dfrac{3}{10}=\dfrac{-12}{30}-\dfrac{9}{30}=-\dfrac{21}{30}\)