Tính nhanh : 5/6 x 1/7 + 5/6 x 4/7 + 5/6 x 2/7 + 18
2 câu trả lời
`5/6 xx 1/7 + 5/6 xx 4/7 + 5/6 xx 2/7 + 18`
`= 5/6 xx ( 1/7 + 4/7 + 2/7 ) + 18`
`= 5/6 xx 1 + 18`
`= 5/6 + 18`
`= 113/6`
$\dfrac{5}{6}$ × $\dfrac{1}{7}$ + $\dfrac{5}{6}$ × $\dfrac{4}{7}$ + $\dfrac{5}{6}$ × $\dfrac{2}{7}$ + 18
= $\dfrac{5}{6}$ × ( $\dfrac{1}{7}$ + $\dfrac{4}{7}$ + $\dfrac{2}{7}$ ) + 18
= $\dfrac{5}{6}$ × $\dfrac{7}{7}$ + 18
= $\dfrac{5}{6}$ × 1 + 18
= $\dfrac{5}{6}$ + 18
= $\dfrac{5}{6}$ + $\dfrac{108}{6}$
= $\dfrac{113}{6}$