\(=\dfrac{2}{3}\left(\dfrac{2}{10}+\dfrac{3}{10}+\dfrac{5}{10}\right)\)
\(=\dfrac{2}{3}\times1=\dfrac{2}{3}\)
`= 2/3 xx (2.10 + 3/10 + 5/10)`
`= 2/3 xx 1`
`= 2/3`
\(=\dfrac{2}{3}\times\left(\dfrac{2}{10}+\dfrac{3}{10}+\dfrac{5}{10}\right)=\dfrac{2}{3}\times1=\dfrac{2}{3}\)
Bài 3:
Ta có: `2` `dm` `1` `cm` `=` `21` `cm`
Chiều cao là:
`21 xx 3/7 = 9` (`cm`)
Diện tích là:
`21 xx 9 = 189` (`cm^2`)