a ) 10/3 - 8/3
11/4 - 5/4
32/17 + 21/17
b ) 5/6 + 7/8
3/7 - 5/14
7/4 - 3/5
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NT
0
27 tháng 7 2021
a) Ta có: \(\dfrac{-5}{7}\left(\dfrac{14}{5}-\dfrac{7}{10}\right):\left|-\dfrac{2}{3}\right|-\dfrac{3}{4}\left(\dfrac{8}{9}+\dfrac{16}{3}\right)+\dfrac{10}{3}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)
\(=\dfrac{-5}{7}\cdot\dfrac{3}{2}\cdot\dfrac{21}{10}-\dfrac{3}{4}\cdot\dfrac{56}{3}+\dfrac{10}{3}\cdot\dfrac{8}{15}\)
\(=\dfrac{-9}{4}-14+\dfrac{16}{9}\)
\(=\dfrac{-1621}{126}\)
b) Ta có: \(\dfrac{17}{-26}\cdot\left(\dfrac{1}{6}-\dfrac{5}{3}\right):\dfrac{17}{13}-\dfrac{20}{3}\left(\dfrac{2}{5}-\dfrac{1}{4}\right)+\dfrac{2}{3}\left(\dfrac{6}{5}-\dfrac{9}{2}\right)\)
\(=\dfrac{-17}{26}\cdot\dfrac{13}{17}\cdot\dfrac{-3}{2}-\dfrac{20}{3}\cdot\dfrac{3}{20}+\dfrac{2}{3}\cdot\dfrac{-33}{10}\)
\(=\dfrac{3}{4}-1-\dfrac{11}{5}\)
\(=-\dfrac{49}{20}\)
LK
7 tháng 4 2017
a. \(\dfrac{3}{4}\) : x - \(\dfrac{17}{5}\) = \(\dfrac{7}{10}\)
\(\dfrac{3}{4}\) : x = \(\dfrac{7}{10}\) + \(\dfrac{17}{5}\)
\(\dfrac{3}{4}\) : x = \(\dfrac{41}{10}\)
x = \(\dfrac{3}{4}\) : \(\dfrac{41}{10}\)
x = \(\dfrac{3}{4}\) . \(\dfrac{10}{41}\)
x = \(\dfrac{15}{82}\)
Vậy x = \(\dfrac{15}{82}\)
16 tháng 1 2022
b: \(27D=3^{14}+3^{17}+...+3^{2024}\)
\(\Leftrightarrow26D=3^{2024}-3^{11}\)
hay \(D=\dfrac{3^{2024}-3^{11}}{26}\)
c: \(25E=-5^4-5^6-...-5^{1002}\)
\(\Leftrightarrow24E=-5^{1002}+5^2\)
hay \(E=\dfrac{-5^{1002}+5^2}{24}\)
NT
2
1 tháng 7 2021
`sqrt{5+2sqrt6}`
`=sqrt{3+2sqrt3sqrt2+2}`
`=sqrt{(sqrt3+sqrt2)^2}`
`=|sqrt3+sqrt2|=sqrt3+sqrt2`
1 tháng 7 2021
`7. sqrt(4+2sqrt3)`
`=sqrt{3+2sqrt3+1}`
`=sqrt{(sqrt3+1)^2}`
`=sqrt3+1`
`8. sqrt(4-2sqrt3)`
`=sqrt{3-2sqrt3+1}`
`=sqrt{(sqrt3-1)^2}`
`=sqrt3-1`
`9. sqrt(11-2sqrt(30))`
`=sqrt{6-2sqrt5sqrt6+5}`
`=sqrt{(sqrt6-sqrt5)^2}`
`=sqrt6-sqrt5`
`10. sqrt(21-4sqrt(17))`
`=sqrt{17-2.2.sqrt{17}+4}`
`=sqrt{(sqrt{17}-2)^2}`
`=sqrt{17}-2`
a: 10/3-8/3=2/3
11/4-5/4=6/4=3/2
32/17+21/17=53/17
b: 5/6+7/8=20/24+21/24=41/24
3/7-5/14=6/14-5/14=1/14
7/4-3/5=35/20-12/20=23/20
a: 10/3-8/3=2/3
11/4-5/4=6/4=3/2
32/17+21/17=53/17
b: 5/6+7/8=20/24+21/24=41/24
3/7-5/14=6/14-5/14=1/14
7/4-3/5=35/20-12/20=23/20