A = 2/1*3 + 2/3*5 +2/5*7 +2/7*9 + 2/9*11+2/11*13 +2/13*15 14/08/2021 Bởi Athena A = 2/1*3 + 2/3*5 +2/5*7 +2/7*9 + 2/9*11+2/11*13 +2/13*15
Đáp án: (“.”là nhân nhé bn) $\dfrac{2}{1.3}$+$\dfrac{2}{3.5}$ +$\dfrac{2}{5.7}$ +$\dfrac{2}{7.9}$ +$\dfrac{2}{9.11}$ +$\dfrac{9}{11.13}$ +$\dfrac{2}{13.15}$ =1-$\dfrac{1}{3}$-$\dfrac{1}{5}$ +$\dfrac{1}{5}$ -$\dfrac{1}{7}$ +$\dfrac{1}{7}$ -$\dfrac{1}{9}$ +$\dfrac{1}{9}$-$\dfrac{1}{11}$+$\dfrac{1}{11}$-$\dfrac{1}{13}$+$\dfrac{1}{13}$-$\dfrac{1}{15}$ =1-$\dfrac{1}{15}$ =$\dfrac{15}{15}$-$\dfrac{1}{15}$ =$\dfrac{14}{15}$ @ChichooKim95 Bình luận
Đáp án: `A = 14/15` Giải thích các bước giải: `A = 2/(1xx3) + 2/(3xx5) + 2/(5xx7) + 2/(7xx9) + 2/(9xx11) + 2/(11xx13) + 2/(13xx15)` `A = 1 – 1/3 + 1/3 – 1/5 + 1/5 – 1/7 + 1/7 – 1/9 + 1/9 – 1/11 + 1/11 – 1/13 + 1/13 – 1/15` `A = 1 – 1/15` `A = 15/15 – 1/15` `A = 14/15` Bình luận
Đáp án: (“.”là nhân nhé bn)
$\dfrac{2}{1.3}$+$\dfrac{2}{3.5}$ +$\dfrac{2}{5.7}$ +$\dfrac{2}{7.9}$ +$\dfrac{2}{9.11}$ +$\dfrac{9}{11.13}$ +$\dfrac{2}{13.15}$
=1-$\dfrac{1}{3}$-$\dfrac{1}{5}$ +$\dfrac{1}{5}$ -$\dfrac{1}{7}$ +$\dfrac{1}{7}$ -$\dfrac{1}{9}$ +$\dfrac{1}{9}$-$\dfrac{1}{11}$+$\dfrac{1}{11}$-$\dfrac{1}{13}$+$\dfrac{1}{13}$-$\dfrac{1}{15}$
=1-$\dfrac{1}{15}$
=$\dfrac{15}{15}$-$\dfrac{1}{15}$
=$\dfrac{14}{15}$
@ChichooKim95
Đáp án: `A = 14/15`
Giải thích các bước giải:
`A = 2/(1xx3) + 2/(3xx5) + 2/(5xx7) + 2/(7xx9) + 2/(9xx11) + 2/(11xx13) + 2/(13xx15)`
`A = 1 – 1/3 + 1/3 – 1/5 + 1/5 – 1/7 + 1/7 – 1/9 + 1/9 – 1/11 + 1/11 – 1/13 + 1/13 – 1/15`
`A = 1 – 1/15`
`A = 15/15 – 1/15`
`A = 14/15`