Thực hiện phép tính( hợp lí nếu có thể)
\(\dfrac{1}{2}+\dfrac{3}{4}-\left(\dfrac{3}{4}-\dfrac{4}{5}\right)\)
\(\dfrac{-3}{7}+\dfrac{3}{4}:\dfrac{3}{14}\)
\(5-\dfrac{7}{39}:\dfrac{7}{13}+\dfrac{8}{9}:4\)
\(1\dfrac{13}{15}.0,75-\left(\dfrac{11}{20}+25\%\right):\dfrac{7}{3}\)
\(\left(\dfrac{5}{12}:\dfrac{11}{6}+\dfrac{5}{12}:\dfrac{11}{5}\right)--\dfrac{7}{12}\)
làm nhanh cho mình nha!!!!Thank nhìu
\(\dfrac{1}{2}+\dfrac{3}{4}-\left(\dfrac{3}{4}-\dfrac{4}{5}\right)\\ =\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{3}{4}+\dfrac{4}{5}\\ =\dfrac{1}{2}+\left(\dfrac{3}{4}-\dfrac{3}{4}\right)+\dfrac{4}{5}\\ =\dfrac{1}{2}+0+\dfrac{4}{5}\\ =\dfrac{1}{2}+\dfrac{4}{5}\\ =\dfrac{5}{10}+\dfrac{8}{10}\\ =\dfrac{13}{10}\)
\(\dfrac{-3}{7}+\dfrac{3}{4}:\dfrac{3}{14}\\ =\dfrac{-3}{7}+\dfrac{3}{4}\cdot\dfrac{14}{3}\\ =\dfrac{-3}{7}+\dfrac{7}{2}\\ =\dfrac{-6}{14}+\dfrac{49}{14}\\ =\dfrac{43}{14}\)
\(1\dfrac{13}{15}.0,75-\left(\dfrac{11}{20}+25\%\right):\dfrac{7}{3}\\ =\dfrac{28}{15}.\dfrac{3}{4}-\left(\dfrac{11}{20}+\dfrac{1}{4}\right):\dfrac{7}{3}\\ =\dfrac{7}{5}-\left(\dfrac{11}{20}+\dfrac{5}{20}\right):\dfrac{7}{3}\\ =\dfrac{7}{5}-\dfrac{4}{5}:\dfrac{7}{3}\\ =\dfrac{7}{5}-\dfrac{4}{5}.\dfrac{3}{7}\\ =\dfrac{7}{5}-\dfrac{12}{35}\\ =\dfrac{49}{35}-\dfrac{12}{35}\\ =\dfrac{37}{35}\)
a, \(\dfrac{1}{2}+\dfrac{3}{4}-\left(\dfrac{3}{4}-\dfrac{4}{5}\right)\)
\(=\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{3}{4}+\dfrac{4}{5}\)
\(=\dfrac{1}{2}+\left(\dfrac{3}{4}-\dfrac{3}{4}\right)+\dfrac{4}{5}\)
\(=\dfrac{1}{2}+0+\dfrac{4}{5}\)
\(=\dfrac{13}{10}\)
b, \(-\dfrac{3}{7}+\dfrac{3}{4}:\dfrac{3}{14}\)
\(=-\dfrac{3}{7}+\dfrac{7}{2}\)
\(=\dfrac{43}{14}\)
c, \(5-\dfrac{7}{39}:\dfrac{7}{13}+\dfrac{8}{9}:4\)
\(=5+\dfrac{1}{3}+\dfrac{2}{9}\)
\(=\dfrac{50}{9}\)
\(5-\dfrac{7}{39}:\dfrac{7}{13}+\dfrac{8}{9}:4\\ =5-\dfrac{7}{39}.\dfrac{13}{7}+\dfrac{8}{9}.\dfrac{1}{4}\\ =5-\dfrac{1}{3}+\dfrac{2}{9}\\ =\dfrac{45}{9}-\dfrac{3}{9}+\dfrac{2}{9}\\ =\dfrac{44}{9}\)
\(\left(\dfrac{5}{12}:\dfrac{11}{6}+\dfrac{5}{12}:\dfrac{11}{5}\right)--\dfrac{7}{12}\\ =\left(\dfrac{5}{22}+\dfrac{25}{132}\right)+\dfrac{7}{12}\\ =\left(\dfrac{30}{132}+\dfrac{25}{132}\right)+\dfrac{7}{12}\\ =\dfrac{5}{12}+\dfrac{7}{12}\\ =1\)
