tính thuận tiện \(\dfrac{4}{9}\) -\(\dfrac{1}{6}\) + \(\dfrac{5}{9}\) + 2 \(\dfrac{2x8x11x9}{9x11x2x5}\) = \(\dfrac{4}{5}\) x \(\dfrac{3}{7}\) + \(\dfrac{4}{5}\) x\(\dfrac{6}{7}\)

\(\dfrac{4}{9}-\dfrac{1}{6}+\dfrac{5}{9}+2\)

\(=\left(\dfrac{4}{9}+\dfrac{5}{9}\right)+2-\dfrac{1}{6}\)

\(=1+2-\dfrac{1}{6}=3-\dfrac{1}{6}=\dfrac{17}{6}\)

\(\dfrac{2\times8\times11\times9}{9\times11\times2\times5}=\dfrac{2}{2}\times\dfrac{9}{9}\times\dfrac{11}{11}\times\dfrac{8}{5}=\dfrac{8}{5}\)

\(\dfrac{4}{5}\times\dfrac{3}{7}+\dfrac{4}{5}\times\dfrac{6}{7}-\dfrac{4}{5}\times\dfrac{2}{7}\)

\(=\dfrac{4}{5}\times\left(\dfrac{3}{7}+\dfrac{6}{7}-\dfrac{2}{7}\right)\)

\(=\dfrac{4}{5}\times1=\dfrac{4}{5}\)

Hãy giúp mọi người biết câu trả lời này thế nào?

51 vote