Question

Tính hợp lý nếu có thể:

Answer 1

b: \(\dfrac{3}{4}-\dfrac{7}{15}+\dfrac{1}{4}+\dfrac{1}{2022}-\dfrac{8}{15}\)

\(=\left(\dfrac{3}{4}+\dfrac{1}{4}\right)-\left(\dfrac{7}{15}+\dfrac{8}{15}\right)+\dfrac{1}{2022}\)

\(=1-1+\dfrac{1}{2022}=\dfrac{1}{2022}\)

c: \(\dfrac{3}{5}\cdot\dfrac{4}{7}+\dfrac{3}{7}\cdot\dfrac{9}{5}+\dfrac{13}{7}\cdot\dfrac{2}{5}\)

\(=\dfrac{3}{5}\cdot\dfrac{4}{7}+\dfrac{3}{5}\cdot\dfrac{9}{7}+\dfrac{13}{7}\cdot\dfrac{2}{5}\)

\(=\dfrac{3}{5}\left(\dfrac{4}{7}+\dfrac{9}{7}\right)+\dfrac{13}{7}\cdot\dfrac{2}{5}\)

\(=\dfrac{3}{5}\cdot\dfrac{13}{7}+\dfrac{13}{7}\cdot\dfrac{2}{5}\)

\(=\dfrac{13}{7}\left(\dfrac{3}{5}+\dfrac{2}{5}\right)=\dfrac{13}{7}\)