Question

[Nguyễn Thái Bảo Châu]

1, \(\dfrac{3}{4}\). ( \(\dfrac{2}{5}\) - \(\dfrac{1}{15}\)) +\(\dfrac{3}{4}\)

2, \(\dfrac{4}{9}\). (\(\dfrac{-13}{3}\)) + \(\dfrac{4}{3}\). \(\dfrac{40}{9}\)

 3, \(\dfrac{4}{9}\) - \(\dfrac{2}{3}\). ( \(\dfrac{4}{5}\)+\(\dfrac{1}{2}\) )

giúp mình nha cảm ơn

Answer 1

[ミ★Zero ❄ ( Hoàng Nhật )]

1, \(\dfrac{3}{4}.\left(\dfrac{2}{5}-\dfrac{1}{15}\right)+\dfrac{3}{4}=\dfrac{3}{4}.\left(\dfrac{2}{5}-\dfrac{1}{15}+1\right)\)

\(=\dfrac{3}{4}.\dfrac{6-1+15}{15}=\dfrac{3}{4}.\dfrac{20}{15}=\dfrac{3}{4}.\dfrac{4}{3}=1\)

2, \(\dfrac{4}{9}.\left(-\dfrac{13}{3}\right)+\dfrac{4}{3}.\dfrac{40}{9}=\dfrac{4}{9}.\left(-\dfrac{13}{3}\right)+\dfrac{4}{9}.\dfrac{40}{3}\)

\(=\dfrac{4}{9}.\left[\left(-\dfrac{13}{3}\right)+\dfrac{40}{3}\right]=\dfrac{4}{9}.9=4\)

3, \(\dfrac{4}{9}-\dfrac{2}{3}.\left(\dfrac{4}{5}+\dfrac{1}{2}\right)=\dfrac{2}{3}\left(\dfrac{2}{3}-\dfrac{4}{5}-\dfrac{1}{2}\right)\)

\(=\dfrac{2}{3}.\dfrac{20-24-15}{30}=\dfrac{2}{3}.\left(-\dfrac{19}{30}\right)=-\dfrac{19}{45}\)

Answer 2

[Thầy Hùng Olm]

1.   \(\dfrac{3}{4}.\left(\dfrac{6}{15}-\dfrac{1}{15}\right)+\dfrac{3}{4}=\dfrac{3}{4}.\dfrac{1}{3}+\dfrac{3}{4}=\dfrac{1}{4}+\dfrac{3}{4}=1\)