Tính: B = 1/3.4 – 1/4.5 – 1/5.6 – 1/6.7 – 1/7.8 – 1/8.9 – 1/9.10 04/09/2021 Bởi Samantha Tính: B = 1/3.4 – 1/4.5 – 1/5.6 – 1/6.7 – 1/7.8 – 1/8.9 – 1/9.10
Đáp án: `B=`$\frac{1}{3.4}$ – $\frac{1}{4.5}$ -…-$\frac{1}{9.10}$ `B=“1/3`-`1/4`+`1/4`-`1/5`+…+`1/9`-`1/10` `B=“1/3` -`1/4`-`1/4`+ `1/10` `B=` `-1/15` Bình luận
$B = \dfrac{1}{3.4} – \dfrac{1}{4.5} – \dfrac{1}{5.6} – \dfrac{1}{6.7} – \dfrac{1}{7.8} – \dfrac{1}{8.9} – \dfrac{1}{9.10}$ $B = \dfrac{1}{3} – \dfrac{1}{4} – (\dfrac{1}{4} – \dfrac{1}{5}) – (\dfrac{1}{5} – \dfrac{1}{6}) – (\dfrac{1}{6} – \dfrac{1}{7}) – (\dfrac{1}{7} – \dfrac{1}{8}) – (\dfrac{1}{8} – \dfrac{1}{9}) – (\dfrac{1}{9} – \dfrac{1}{10})$ $B = \dfrac{1}{3} – \dfrac{1}{4} – \dfrac{1}{4} + \dfrac{1}{10} = -\dfrac{1}{15}$ Bình luận
Đáp án:
`B=`$\frac{1}{3.4}$ – $\frac{1}{4.5}$ -…-$\frac{1}{9.10}$
`B=“1/3`-`1/4`+`1/4`-`1/5`+…+`1/9`-`1/10`
`B=“1/3` -`1/4`-`1/4`+ `1/10`
`B=` `-1/15`
$B = \dfrac{1}{3.4} – \dfrac{1}{4.5} – \dfrac{1}{5.6} – \dfrac{1}{6.7} – \dfrac{1}{7.8} – \dfrac{1}{8.9} – \dfrac{1}{9.10}$
$B = \dfrac{1}{3} – \dfrac{1}{4} – (\dfrac{1}{4} – \dfrac{1}{5}) – (\dfrac{1}{5} – \dfrac{1}{6}) – (\dfrac{1}{6} – \dfrac{1}{7}) – (\dfrac{1}{7} – \dfrac{1}{8}) – (\dfrac{1}{8} – \dfrac{1}{9}) – (\dfrac{1}{9} – \dfrac{1}{10})$
$B = \dfrac{1}{3} – \dfrac{1}{4} – \dfrac{1}{4} + \dfrac{1}{10} = -\dfrac{1}{15}$