Bài 1:
a) \(\dfrac{2}{3}\times\dfrac{4}{5}:\dfrac{3}{5}=\dfrac{8}{15}\times\dfrac{5}{3}=\dfrac{40}{45}=\dfrac{8}{9}\)
b) \(\dfrac{4}{7}:\dfrac{2}{5}\times\dfrac{21}{25}=\dfrac{4}{7}\times\dfrac{5}{2}\times\dfrac{21}{25}=\dfrac{20}{14}\times\dfrac{21}{25}=\dfrac{10}{7}\times\dfrac{21}{25}=\dfrac{210}{175}=\dfrac{6}{5}\)
Bài 2:
Cạnh của miếng bìa hình vuông đó là: \(\dfrac{8}{3}:4=\dfrac{2}{3}\left(m\right)\)
Diện tích miếng bìa hình vuông đó là: \(\dfrac{2}{3}\times\dfrac{2}{3}=\dfrac{4}{9}\left(m^2\right)\)
`1) a) 2/3 xx 4/5 : 3/5 = 8/15 : 5/3 = 8/15 xx 3/5 = ( 8 xx 3 ) / ( 5 xx 3 xx 5 ) = 8/25`
`b) 4/7 : 2/5 xx 21/25 = 4/7 xx 5/2 xx 21/25 =` \(\dfrac{4\times5\times7\times3}{7\times2\times5\times5}=\dfrac{4\times3}{2\times5}=\dfrac{12}{10}=\dfrac{6}{5}\)
`2)` Cạnh : `8/3 : 4= 8/3 xx 1/4 = 8/12 = 2/3`
Diện tích : `2/3 xx 2/3 = 4/9`
1)
a)
\(\dfrac{2}{3}\cdot\dfrac{4}{5}:\dfrac{3}{5}=\dfrac{8}{15}:\dfrac{3}{5}=\dfrac{8}{15}\cdot\dfrac{5}{3}=\dfrac{8}{9},\)
b)
\(\dfrac{4}{7}:\dfrac{2}{5}\cdot\dfrac{21}{25}=\dfrac{4}{7}\cdot\dfrac{5}{2}\cdot\dfrac{21}{25}=\dfrac{4\cdot5\cdot21}{7\cdot2\cdot25}=\dfrac{6}{5}\)
2)
dien tich mieng bia hinh vuong la
\(\left(\dfrac{8}{3}:4\right)\cdot\left(\dfrac{8}{3}:4\right)=\dfrac{4}{9}\left(m^2\right)\)
ds
4 và 5
