\(\dfrac{1}{2}\)-1).(\(\dfrac{1}{3}\)-1).(

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HH
hello hello
14 tháng 3 2018
1. tính hợp lí a. A=\(\dfrac{1}{3}\)+\(\dfrac{-3}{4}\)+\(\dfrac{3}{5}\)+\(\dfrac{1}{57}\)+\(\dfrac{-1}{36}\)+\(\dfrac{1}{15}\)+\(\dfrac{-2}{9}\) b. B=\(\dfrac{1}{2}\)+\(\dfrac{-1}{5}\)+\(\dfrac{-5}{7}\)+\(\dfrac{1}{6}\)+\(\dfrac{-3}{35}\)+\(\dfrac{1}{3}\)+\(\dfrac{1}{41}\) c....
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1. tính hợp lí

a. A=\(\dfrac{1}{3}\)+\(\dfrac{-3}{4}\)+\(\dfrac{3}{5}\)+\(\dfrac{1}{57}\)+\(\dfrac{-1}{36}\)+\(\dfrac{1}{15}\)+\(\dfrac{-2}{9}\)

b. B=\(\dfrac{1}{2}\)+\(\dfrac{-1}{5}\)+\(\dfrac{-5}{7}\)+\(\dfrac{1}{6}\)+\(\dfrac{-3}{35}\)+\(\dfrac{1}{3}\)+\(\dfrac{1}{41}\)

c. C=\(\dfrac{-1}{2}\)+\(\dfrac{3}{5}\)+\(\dfrac{-1}{9}\)+\(\dfrac{1}{107}\)+\(\dfrac{-7}{18}\)+\(\dfrac{4}{35}\)+\(\dfrac{2}{7}\)
#Hỏi cộng đồng OLM #Toán lớp 6
1
NL
Nguyễn Lê Phước Thịnh
25 tháng 6 2022

a: \(A=\left(\dfrac{-3}{4}+\dfrac{-2}{9}-\dfrac{1}{36}\right)+\left(\dfrac{1}{3}+\dfrac{1}{15}+\dfrac{3}{5}\right)+\dfrac{1}{57}\)

\(=\dfrac{-27-8-1}{36}+\dfrac{5+1+9}{15}+\dfrac{1}{57}\)

=1/57

b: \(B=\left(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{3}\right)+\left(\dfrac{-1}{5}-\dfrac{5}{7}-\dfrac{3}{35}\right)+\dfrac{1}{41}\)

\(=\dfrac{3+1+2}{6}+\dfrac{-7-25-3}{35}+\dfrac{1}{41}\)

=1/41

c: \(C=\left(\dfrac{-1}{2}-\dfrac{1}{9}-\dfrac{7}{18}\right)+\left(\dfrac{3}{5}+\dfrac{2}{7}+\dfrac{4}{35}\right)+\dfrac{1}{107}\)

=1-1+1/107

=1/107

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ND
Nguyễn Đa Tiến
30 tháng 3 2018
tìm x biết a) \(\dfrac{2}{3}\): x - \(\dfrac{5}{6}\)= 1\(\dfrac{1}{2}\) b) (\(\dfrac{5}{6}\) . x + \(\dfrac{2}{3}\)) : (\(\dfrac{2}{5}\) +\(1\dfrac{1}{3}\) )\(\dfrac{4}{9}\) c) \(|\)x - \(\dfrac{4}{3}\)\(|\) - \(\dfrac{5}{6}\) = \(\dfrac{3}{5}\) . \(1\dfrac{1}{2}\) d) \(|\)2x + \(\dfrac{1}{2}\)\(|\) - \(\dfrac{3}{4}\)=\(3\dfrac{1}{2}\) e) \(|\dfrac{3}{2}\)x - \(\dfrac{5}{6}|\)+ \(\dfrac{12}{5}\)=...
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tìm x biết

a) \(\dfrac{2}{3}\): x - \(\dfrac{5}{6}\)= 1\(\dfrac{1}{2}\)

b) (\(\dfrac{5}{6}\) . x + \(\dfrac{2}{3}\)) : (\(\dfrac{2}{5}\) +\(1\dfrac{1}{3}\) )\(\dfrac{4}{9}\)

c) \(|\)x - \(\dfrac{4}{3}\)\(|\) - \(\dfrac{5}{6}\) = \(\dfrac{3}{5}\) . \(1\dfrac{1}{2}\)

d) \(|\)2x + \(\dfrac{1}{2}\)\(|\) - \(\dfrac{3}{4}\)=\(3\dfrac{1}{2}\)

e) \(|\dfrac{3}{2}\)x - \(\dfrac{5}{6}|\)+ \(\dfrac{12}{5}\)= \(1\dfrac{1}{2}\)
#Hỏi cộng đồng OLM #Toán lớp 6
1
ND
Nguyễn Đa Tiến
30 tháng 3 2018

các bạn ơi giúp mìh với mìh đag cần gấp ai nhanh và đúng thì mih tick cho

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NN
Nguyen Ngoc Anh
3 tháng 4 2017
Tính giá trị biểu...
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Tính giá trị biểu thức:

C=\(\dfrac{-1}{7}\)x\(\dfrac{5}{9}\)+\(\dfrac{-5}{9}\)x\(\dfrac{1}{7}\)+\(\dfrac{-5}{9}\)x\(\dfrac{5}{7}\)

D=\(\dfrac{4}{2x3}\)+\(\dfrac{4}{3x4}\)+\(\dfrac{4}{4x5}\)+....+\(\dfrac{4}{8x9}\)

A=\(\dfrac{5}{9}\)-\(\dfrac{5}{8}\)+\(\dfrac{2}{3}\)+\(\dfrac{4}{9}\)+\(\dfrac{-3}{8}\)+\(\dfrac{1}{3}\)

B=\(\dfrac{1}{2}\)+\(\dfrac{1}{6}\)+\(\dfrac{1}{12}\)+\(\dfrac{1}{20}\)+\(\dfrac{1}{30}\)+\(\dfrac{1}{42}\)+\(\dfrac{1}{56}\)
#Hỏi cộng đồng OLM #Toán lớp 6
4
JP
Jenny Phạm
3 tháng 4 2017

B=\(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{30}+\dfrac{1}{42}+\dfrac{1}{56}\)

B=\(\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+\dfrac{1}{4.5}+\dfrac{1}{5.6}+\dfrac{1}{6.7}+\dfrac{1}{7.8}\)

B=\(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{8}\)

B= 1-\(\dfrac{1}{8}\)

B= \(\dfrac{7}{8}\)

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MV
Mới vô
24 tháng 4 2017

\(A=\dfrac{5}{9}-\dfrac{5}{8}+\dfrac{2}{3}+\dfrac{4}{9}+\dfrac{-3}{8}+\dfrac{1}{3}\\ =\dfrac{5}{9}+\dfrac{-5}{8}+\dfrac{2}{3}+\dfrac{4}{9}+\dfrac{-3}{8}+\dfrac{1}{3}\\= \left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\left(\dfrac{2}{3}+\dfrac{1}{3}\right)+\left(\dfrac{-5}{8}+\dfrac{-3}{8}\right)\\ =1+1+\left(-1\right)\\ =2+\left(-1\right)\\ =1\)

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VM
van mai huong
21 tháng 3 2017
1.Tính a) (\(\dfrac{-2}{3}\)+1\(\dfrac{1}{4}\)-\(\dfrac{1}{6}\)).\(\dfrac{-24}{10}\) b) \(\dfrac{13}{15}\).0,25.3+(\(\dfrac{8}{15}\)-\(1\dfrac{19}{60}\)):\(1\dfrac{23}{24}\) c) (\(\dfrac{12}{32}\)+\(\dfrac{5}{-20}\)-\(\dfrac{10}{24}\)):\(\dfrac{2}{3}\) d) \(4\dfrac{1}{2}\):(2,5-\(3\dfrac{3}{4}\))+(\(\dfrac{-1}{2}\))\(^2\) e) \(\dfrac{-5}{2}\):(\(\dfrac{3}{4}\)-\(\dfrac{1}{2}\)) 2. Tính nhanh a)...
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1.Tính

a) (\(\dfrac{-2}{3}\)+1\(\dfrac{1}{4}\)-\(\dfrac{1}{6}\)).\(\dfrac{-24}{10}\)

b) \(\dfrac{13}{15}\).0,25.3+(\(\dfrac{8}{15}\)-\(1\dfrac{19}{60}\)):\(1\dfrac{23}{24}\)

c) (\(\dfrac{12}{32}\)+\(\dfrac{5}{-20}\)-\(\dfrac{10}{24}\)):\(\dfrac{2}{3}\)

d) \(4\dfrac{1}{2}\):(2,5-\(3\dfrac{3}{4}\))+(\(\dfrac{-1}{2}\))\(^2\)

e) \(\dfrac{-5}{2}\):(\(\dfrac{3}{4}\)-\(\dfrac{1}{2}\))

2. Tính nhanh

a) \(\dfrac{5}{23}\).\(\dfrac{17}{26}\)+\(\dfrac{5}{23}\).\(\dfrac{10}{26}\)-\(\dfrac{5}{23}\)

b) \(\dfrac{1}{7}\).\(\dfrac{5}{9}\)+\(\dfrac{5}{9}\).\(\dfrac{2}{7}\)+\(\dfrac{5}{9}\).\(\dfrac{1}{7}\)+\(\dfrac{5}{9}\).\(\dfrac{3}{7}\)
#Hỏi cộng đồng OLM #Toán lớp 6
2
NL
Nanami Luchia
21 tháng 3 2017

2) Tinh nhanh:

a) \(\dfrac{5}{23}\) . \(\dfrac{17}{26}\) + \(\dfrac{5}{23}\) . \(\dfrac{10}{26}\) - \(\dfrac{5}{23}\)

= \(\dfrac{5}{23}\) . \(\left(\dfrac{17}{26}+\dfrac{10}{26}-1\right)\)

= \(\dfrac{5}{23}\) . \(\left(\dfrac{27}{26}-1\right)\) = \(\dfrac{5}{23}\) . \(\dfrac{1}{26}\)

= \(\dfrac{5}{598}\)

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NL
Nanami Luchia
21 tháng 3 2017

b) \(\dfrac{1}{7}.\dfrac{5}{9}+\dfrac{5}{9}.\dfrac{2}{7}+\dfrac{5}{9}.\dfrac{1}{7}+\dfrac{5}{9}.\dfrac{3}{7}\)

= \(\dfrac{5}{9}.\left(\dfrac{1}{7}+\dfrac{2}{7}+\dfrac{1}{7}+\dfrac{3}{7}\right)\)

= \(\dfrac{5}{9}\) . 1= \(\dfrac{5}{9}\)

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CV
Cute Vô Đối
25 tháng 7 2018
1. Tìm x, biết: a, \(1\dfrac{3}{5}\) + \(\dfrac{\dfrac{2}{7}+\dfrac{2}{17}+\dfrac{2}{37}}{\dfrac{5}{7}+\dfrac{5}{17}+\dfrac{5}{37}}\) . x = \(\dfrac{16}{5}\) b, (\(\dfrac{1}{24.25}\) + \(\dfrac{1}{25.26}\) + . . . + \(\dfrac{1}{39.40}\) ) . 120 + x. \(\dfrac{1}{3}\) = -4 c, \(\left|x-\dfrac{1}{3}\right|\) . 2 + \(\dfrac{4}{5}\) = 0,24 d, \(\dfrac{24}{7x-3}\) = \(\dfrac{-4}{25}\) e, ( 50% x + \(5\dfrac{1}{4}\) ) , \(\dfrac{-2}{3}\) = \(2\dfrac{5}{6}\) f, \(1\dfrac{1}{3}\) -...
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1. Tìm x, biết:

a, \(1\dfrac{3}{5}\) + \(\dfrac{\dfrac{2}{7}+\dfrac{2}{17}+\dfrac{2}{37}}{\dfrac{5}{7}+\dfrac{5}{17}+\dfrac{5}{37}}\) . x = \(\dfrac{16}{5}\)

b, (\(\dfrac{1}{24.25}\) + \(\dfrac{1}{25.26}\) + . . . + \(\dfrac{1}{39.40}\) ) . 120 + x. \(\dfrac{1}{3}\) = -4

c, \(\left|x-\dfrac{1}{3}\right|\) . 2 + \(\dfrac{4}{5}\) = 0,24

d, \(\dfrac{24}{7x-3}\) = \(\dfrac{-4}{25}\)

e, ( 50% x + \(5\dfrac{1}{4}\) ) , \(\dfrac{-2}{3}\) = \(2\dfrac{5}{6}\)

f, \(1\dfrac{1}{3}\) - 25%\(\dfrac{-5}{12}\) + 2x = 1,6 : \(\dfrac{3}{5}\)
#Hỏi cộng đồng OLM #Toán lớp 6
1
NL
Nguyễn Lê Phước Thịnh
23 tháng 8 2022

a: \(\Leftrightarrow\dfrac{8}{5}+\dfrac{2}{5}\cdot x=\dfrac{16}{5}\)

=>2/5x=8/5

=>x=4

b: \(\Leftrightarrow\left(\dfrac{1}{24}-\dfrac{1}{25}+\dfrac{1}{25}-\dfrac{1}{26}+...+\dfrac{1}{39}-\dfrac{1}{40}\right)\cdot120+\dfrac{1}{3}x=-4\)

\(\Leftrightarrow x\cdot\dfrac{1}{3}+2=-4\)

=>1/3x=-6

=>x=-18

c: =>2|x-1/3|=0,24-4/5=-0,56<0

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LK
Lê Khánh Dung
16 tháng 4 2017
1)19 \(\dfrac{5}{8}\) : \(\dfrac{7}{12}\) - 15 \(\dfrac{1}{4}\) : \(\dfrac{7}{12}\) 2) \(\dfrac{2}{5}\) .\(\dfrac{1}{3}\) _ \(\dfrac{2}{15}\) : \(\dfrac{1}{5}\) +\(\dfrac{3}{5}\) .\(\dfrac{1}{3}\) 3) \(\dfrac{4}{9}\). \(19\dfrac{1}{3}\)-\(\dfrac{4}{9}\).\(39\dfrac{1}{3}\) Giúp mình...
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1)19 \(\dfrac{5}{8}\) : \(\dfrac{7}{12}\) - 15 \(\dfrac{1}{4}\) : \(\dfrac{7}{12}\)

2) \(\dfrac{2}{5}\) .\(\dfrac{1}{3}\) _ \(\dfrac{2}{15}\) : \(\dfrac{1}{5}\) +\(\dfrac{3}{5}\) .\(\dfrac{1}{3}\)

3) \(\dfrac{4}{9}\). \(19\dfrac{1}{3}\)-\(\dfrac{4}{9}\).\(39\dfrac{1}{3}\)


Giúp mình nha
#Hỏi cộng đồng OLM #Toán lớp 6
1
ND
Nguyễn Đắc Định
16 tháng 4 2017

1) \(19\dfrac{5}{8}:\dfrac{7}{12}-15\dfrac{1}{4}:\dfrac{7}{12}\)

\(=\dfrac{157}{8}\cdot\dfrac{12}{7}-\dfrac{61}{4}\cdot\dfrac{12}{7}\\ =\dfrac{12}{7}\left(\dfrac{157}{8}-\dfrac{61}{4}\right)\\ =\dfrac{12}{7}\cdot\dfrac{35}{8}\\ =\dfrac{15}{2}\)

2) \(\dfrac{2}{5}\cdot\dfrac{1}{3}-\dfrac{2}{15}:\dfrac{1}{5}+\dfrac{3}{5}\cdot\dfrac{1}{3}\)

\(=\dfrac{1}{3}\left(\dfrac{2}{5}+\dfrac{3}{5}\right)-\dfrac{2}{15}\cdot5\\ =\dfrac{1}{3}\cdot1-\dfrac{2}{3}\\ =\dfrac{1}{3}-\dfrac{2}{3}\\ =-\dfrac{1}{3}\)

3) \(\dfrac{4}{9}\cdot19\dfrac{1}{3}-\dfrac{4}{9}\cdot39\dfrac{1}{3}\)

\(=\dfrac{4}{9}\left(19\dfrac{1}{3}-39\dfrac{1}{3}\right)\\ =\dfrac{4}{9}\cdot\left(\dfrac{58}{3}-\dfrac{118}{3}\right)\\ =\dfrac{4}{9}\cdot\left(-20\right)\\ =-\dfrac{80}{9}\)

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PT
PHẠM THANH BÌNH
18 tháng 4 2018
1) (4\(\dfrac{5}{57}\) - 3\(\dfrac{4}{51}\) + 8\(\dfrac{13}{29}\) ) - ( 3\(\dfrac{5}{57}\) - 6\(\dfrac{16}{29}\) ) 2) \(\dfrac{6}{7}\) + \(\dfrac{5}{8}\) : 5 - \(\dfrac{3}{16}\) . (-2)\(^2\) 3) 1\(\dfrac{13}{15}\) . 0, 75 - ( \(\dfrac{104}{195}\) + 25% ) . \(^{\dfrac{24}{47}}\) - 3\(\dfrac{12}{13}\) :3 4) [ 80% : \(\dfrac{1}{2}\) - 2 . 0, 75 + (-3)\(^2\) . \(\dfrac{1}{6}\) ] : \(\dfrac{1}{10}\) + 1\(\dfrac{1}{5}\) . ( \(\dfrac{1}{3}\) - \(\dfrac{1}{2}\)...
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1) (4\(\dfrac{5}{57}\) - 3\(\dfrac{4}{51}\) + 8\(\dfrac{13}{29}\) ) - ( 3\(\dfrac{5}{57}\) - 6\(\dfrac{16}{29}\) )

2) \(\dfrac{6}{7}\) + \(\dfrac{5}{8}\) : 5 - \(\dfrac{3}{16}\) . (-2)\(^2\)

3) 1\(\dfrac{13}{15}\) . 0, 75 - ( \(\dfrac{104}{195}\) + 25% ) . \(^{\dfrac{24}{47}}\) - 3\(\dfrac{12}{13}\) :3

4) [ 80% : \(\dfrac{1}{2}\) - 2 . 0, 75 + (-3)\(^2\) . \(\dfrac{1}{6}\) ] : \(\dfrac{1}{10}\) + 1\(\dfrac{1}{5}\) . ( \(\dfrac{1}{3}\) - \(\dfrac{1}{2}\) )
#Hỏi cộng đồng OLM #Toán lớp 6
1
PT
PHẠM THANH BÌNH
22 tháng 4 2018

giúp mình đi mà ToT khocroi

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PT
Phạm Thu Huyền
20 tháng 3 2017
Bài 1 Tính a) ( \(\dfrac{-2}{3}\) + \(1\dfrac{1}{4}\) - \(\dfrac{1}{6}\) ) : \(\dfrac{-24}{10}\) b) \(\dfrac{13}{15}\) x 0.25 x 3 + ( \(\dfrac{8}{15}\) - \(1\dfrac{19}{60}\) ) \(1\dfrac{23}{24}\) c) ( \(\dfrac{12}{32}\) + \(\dfrac{5}{-20}\) - \(\dfrac{10}{24}\) ) : \(\dfrac{2}{3}\) d) \(4\dfrac{1}{2}\) : ( 2.5 - \(3\dfrac{3}{4}\) ) + ( -\(\dfrac{1}{2}\) ) e) \(\dfrac{-5}{2}\) : ( \(\dfrac{3}{4}\) - \(\dfrac{1}{2}\)...
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Bài 1 Tính

a) ( \(\dfrac{-2}{3}\) + \(1\dfrac{1}{4}\) - \(\dfrac{1}{6}\) ) : \(\dfrac{-24}{10}\)

b) \(\dfrac{13}{15}\) x 0.25 x 3 + ( \(\dfrac{8}{15}\) - \(1\dfrac{19}{60}\) ) \(1\dfrac{23}{24}\)

c) ( \(\dfrac{12}{32}\) + \(\dfrac{5}{-20}\) - \(\dfrac{10}{24}\) ) : \(\dfrac{2}{3}\)

d) \(4\dfrac{1}{2}\) : ( 2.5 - \(3\dfrac{3}{4}\) ) + ( -\(\dfrac{1}{2}\) )

e) \(\dfrac{-5}{2}\) : ( \(\dfrac{3}{4}\) - \(\dfrac{1}{2}\) )
#Hỏi cộng đồng OLM #Toán lớp 6
1
ND
Nguyễn Đắc Định
20 tháng 3 2017

a , \(\left(\dfrac{-2}{3}+1\dfrac{1}{4}-\dfrac{1}{6}\right):\dfrac{-24}{10}\)

=\(\left(\dfrac{-2}{3}+\dfrac{5}{4}-\dfrac{1}{6}\right):\dfrac{-12}{5}\)

=\(\left(\dfrac{-8}{12}+\dfrac{15}{12}-\dfrac{2}{12}\right)\cdot\dfrac{-5}{12}\)

=\(\dfrac{5}{12}\cdot\dfrac{-5}{12}=\dfrac{-25}{144}\)

b , \(\dfrac{13}{15}\cdot0,25\cdot3+\left(\dfrac{8}{15}-1\dfrac{19}{60}\right)1\dfrac{23}{24}\)

=\(\dfrac{13}{15}\cdot\dfrac{1}{4}\cdot3+\left(\dfrac{8}{15}-\dfrac{79}{60}\right)\cdot\dfrac{57}{24}\)

=\(\dfrac{13}{20}-\dfrac{47}{60}\cdot\dfrac{57}{24}\)

=\(\dfrac{13}{20}-\dfrac{893}{480}=\dfrac{312}{480}-\dfrac{893}{480}=\dfrac{-581}{480}\)

c , \(\left(\dfrac{12}{32}+\dfrac{5}{-20}-\dfrac{10}{24}\right):\dfrac{2}{3}\)

=\(\left(\dfrac{180}{480}-\dfrac{120}{480}-\dfrac{200}{480}\right)\cdot\dfrac{3}{2}\)

= \(\dfrac{-7}{24}\cdot\dfrac{3}{2}=\dfrac{-7}{16}\)

d , \(4\dfrac{1}{2}:\left(2,5-3\dfrac{3}{4}\right)+\left(-\dfrac{1}{2}\right)\)

=\(\dfrac{9}{2}:\left(\dfrac{5}{2}-\dfrac{15}{4}\right)-\dfrac{1}{2}\)

=\(\dfrac{9}{2}:\dfrac{-5}{4}-\dfrac{1}{2}=\dfrac{9}{2}\cdot\dfrac{-4}{5}-\dfrac{1}{2}=\dfrac{-18}{5}-\dfrac{1}{2}=\dfrac{-41}{10}\)

e , \(\dfrac{-5}{2}:\left(\dfrac{3}{4}-\dfrac{1}{2}\right)=\dfrac{-5}{2}\left(\dfrac{3}{4}-\dfrac{2}{4}\right)\)

=\(\dfrac{-5}{2}:\dfrac{1}{4}=\dfrac{-5}{2}\cdot4=-10\)

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LT
Le Thu Trang
25 tháng 7 2018
\(\dfrac{5}{\left|x\right|}\) - \(\dfrac{4}{3}\) = \(\dfrac{38}{24}\) -\(\dfrac{1}{7}\) . ( 9\(\dfrac{1}{2}\) - 8,75 ) : \(\dfrac{2}{7}\) + 0,625 : ( -1\(\dfrac{2}{3}\) ) \(\dfrac{7}{9}\) - \(\dfrac{\left|x\right|}{3}\) = \(\dfrac{1}{9}\) [ \(\dfrac{4}{9}\) + ( \(\dfrac{3}{8}\) x - \(\dfrac{1}{2}\) ) ] . \(\dfrac{6}{11}\) = ...
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\(\dfrac{5}{\left|x\right|}\) - \(\dfrac{4}{3}\) = \(\dfrac{38}{24}\) -\(\dfrac{1}{7}\) . ( 9\(\dfrac{1}{2}\) - 8,75 ) : \(\dfrac{2}{7}\) + 0,625 : ( -1\(\dfrac{2}{3}\) )

\(\dfrac{7}{9}\) - \(\dfrac{\left|x\right|}{3}\) = \(\dfrac{1}{9}\) [ \(\dfrac{4}{9}\) + ( \(\dfrac{3}{8}\) x - \(\dfrac{1}{2}\) ) ] . \(\dfrac{6}{11}\) = \(\dfrac{18}{55}\)

\(\dfrac{2}{9}\) . ( 3x - \(\dfrac{1}{2}\) ) - \(\dfrac{5}{6}\) = -1\(\dfrac{1}{3}\)
#Hỏi cộng đồng OLM #Toán lớp 6
3
PN
Phạm Ngọc Trâm Anh
4 tháng 8 2018

Ôn tập cuối năm phần số học

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PN
Phạm Ngọc Trâm Anh
4 tháng 8 2018

Ôn tập cuối năm phần số học

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NP
Nguyễn Phương Anh
27 tháng 3 2018
Chứng tỏ rằng : (1+\(\dfrac{1}{3}\)+\(\dfrac{1}{5}\)+...+\(\dfrac{1}{99}\)) - (\(\dfrac{1}{2}\)+\(\dfrac{1}{4}\)+\(\dfrac{1}{6}\)+...+\(\dfrac{1}{100}\)) = \(\dfrac{1}{51}\)+ \(\dfrac{1}{52}\)+ \(\dfrac{1}{53}\)+ ...+ \(\dfrac{1}{100}\) ...
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Chứng tỏ rằng :

(1+\(\dfrac{1}{3}\)+\(\dfrac{1}{5}\)+...+\(\dfrac{1}{99}\)) - (\(\dfrac{1}{2}\)+\(\dfrac{1}{4}\)+\(\dfrac{1}{6}\)+...+\(\dfrac{1}{100}\)) = \(\dfrac{1}{51}\)+ \(\dfrac{1}{52}\)+ \(\dfrac{1}{53}\)+ ...+ \(\dfrac{1}{100}\)
#Hỏi cộng đồng OLM #Toán lớp 6
1
NT
Nguyễn Thanh Hằng
27 tháng 3 2018

\(\left(1+\dfrac{1}{3}+\dfrac{1}{5}+.....+\dfrac{1}{99}\right)-\left(\dfrac{1}{2}+\dfrac{1}{4}+.......+\dfrac{1}{100}\right)\)

\(=\left(1+\dfrac{1}{2}+\dfrac{1}{3}+.....+\dfrac{1}{99}+\dfrac{1}{100}\right)-\left(\dfrac{1}{2}+\dfrac{1}{4}+.......+\dfrac{1}{100}\right)-\left(\dfrac{1}{2}+\dfrac{1}{4}+.....+\dfrac{1}{100}\right)\)

\(=\left(1+\dfrac{1}{2}+\dfrac{1}{3}+.....+\dfrac{1}{100}\right)-2\left(\dfrac{1}{2}+\dfrac{1}{4}+.......+\dfrac{1}{100}\right)\)

\(=\left(1+\dfrac{1}{2}+\dfrac{1}{3}+....+\dfrac{1}{100}\right)-\left(1+\dfrac{1}{2}+\dfrac{1}{3}+.....+\dfrac{1}{50}\right)\)

\(=\dfrac{1}{51}+\dfrac{1}{52}+......+\dfrac{1}{100}\)

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