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24 tháng 9 2015

1+2+3+4+5+6+7+8+9+1+2+3+4+5+6+7+8+9+0+0+0+3+4+1+2+3+111+44+99 = 357

1+2+3+4+5+6+7+8+9+1+2+3+4+5+6+7+8+9+0+0+0+3+4+1+2+3+111+44+99=357

2 tháng 10 2018

\(a.\frac{19}{5}\cdot\frac{4}{7}+\frac{3}{7}\cdot\frac{19}{5}-\frac{4}{5}\)

\(=\frac{19}{5}\cdot\left(\frac{4}{7}+\frac{3}{7}\right)-\frac{4}{5}\)

\(=\frac{19}{5}\cdot1-\frac{4}{5}\)

\(=\frac{19}{5}-\frac{4}{5}=\frac{15}{5}=3\)

\(b.2\frac{2}{7}\cdot5\frac{2}{5}+\frac{16}{7}\cdot1\frac{3}{5}+\frac{1}{2}\)

\(=\frac{16}{7}\cdot\frac{27}{5}+\frac{16}{7}\cdot\frac{8}{5}+\frac{1}{2}\)

\(=\frac{16}{7}\cdot\left(\frac{27}{5}+\frac{8}{5}\right)+\frac{1}{2}\)

\(=\frac{16}{7}\cdot7+\frac{1}{2}\)

\(=16+\frac{1}{2}=\frac{33}{2}\)

\(c.\frac{3}{7}\cdot3\frac{3}{4}-\frac{3}{7}\cdot\frac{5}{4}-\frac{1}{4}\)

\(=\frac{3}{7}\cdot\frac{15}{4}-\frac{3}{7}\cdot\frac{5}{4}-\frac{1}{4}\)

\(=\frac{3}{7}\cdot\left(\frac{15}{4}-\frac{5}{4}\right)-\frac{1}{4}\)

\(=\frac{3}{7}\cdot\frac{5}{2}-\frac{1}{4}\)

\(=\frac{15}{14}-\frac{1}{4}=\frac{23}{28}\)

Chú ý: \(\cdot:\times\)

HQ
Hà Quang Minh
Giáo viên
2 tháng 8 2023

\(3\cdot\left(\dfrac{1}{2}-x\right)-5\left(x-\dfrac{1}{10}\right)=-\dfrac{7}{4}\\ \Leftrightarrow-8x=-\dfrac{15}{4}\\ \Leftrightarrow x=\dfrac{15}{32}\)

 

\(4\left(\dfrac{3}{4}+x\right)-\dfrac{1}{5}=7x-\dfrac{1}{7}\\ \Leftrightarrow3x=\dfrac{103}{35}\\ \Leftrightarrow x=\dfrac{103}{105}\)

2 tháng 8 2023

\(3\left(\dfrac{1}{2}-x\right)-5\left(x-\dfrac{1}{10}\right)=-\dfrac{7}{4}\)

\(\Rightarrow\dfrac{3}{2}-3x-5x+\dfrac{1}{2}=-\dfrac{7}{4}\)

\(\Rightarrow2-8x=-\dfrac{7}{4}\)

\(\Rightarrow8x=2+\dfrac{7}{4}\)

\(\Rightarrow8x=\dfrac{15}{4}\)

\(\Rightarrow x=\dfrac{15}{32}\)

___________

\(4\left(\dfrac{3}{4}+x\right)-\dfrac{1}{5}=7x-\dfrac{1}{7}\)

\(\Rightarrow3+4x-\dfrac{1}{5}=7x-\dfrac{1}{7}\)

\(\Rightarrow4x+\dfrac{14}{5}=7x-\dfrac{1}{7}\)

\(\Rightarrow7x-4x=\dfrac{14}{5}+\dfrac{1}{7}\)

\(\Rightarrow3x=\dfrac{103}{35}\)

\(\Rightarrow x=\dfrac{103}{105}\)

30 tháng 3 2015

A = 2/1*5 + 2/5*9 + ... + 2/101*105

   = 1/2(4/1*5 + 4/5*9 + ... + 4/101*105)

   = 1/2(1 - 1/5 + 1/5 - 1/9 + ... + 1/101 - 1/105)

   = 1/2(1 - 1/105)

   = 1/2 * 104/105 = 52/105

Sửa câu b. Phân số thứ 2 phải là 4/5*8

B = 4/2*5 + 4/5*8 + ... + 4/47*50

   = 4/3(3/2*5 + 3/5*8 + ... + 3/47*50)

   = 4/3(1/2 - 1/5 + 1/5 - 1/8 + ... + 1/47 - 1/50)

   = 4/3(1/2 - 1/50)

   = 4/3 * 24/50 = 16/25

 

 

17 tháng 5 2015

44/7 + 38/5 +78/9+ 2/5 + 5/7 +1/3+3/4+1981

= ( 44/7 + 5/7 ) + ( 38/5 +2/5 ) + 26/3 + 1/3 +3/4 +1981

= ( 44/7 + 5/7 ) + ( 38/5 +2/5 ) + ( 26/3 + 1/3 ) + 3/4 + 1981

= 7 + 8 + 9 + 3/4 + 1981

= 3/4 + 2005

= 8023/4

26 tháng 12 2022

  \(\dfrac{37}{4}+\dfrac{44}{7}\) + \(\dfrac{38}{5}\) + \(\dfrac{26}{3}\) + \(\dfrac{1}{3}\) + \(\dfrac{5}{7}\) + \(\dfrac{3}{4}\)

= ( \(\dfrac{37}{4}+\) \(\dfrac{3}{4}\)) + ( \(\dfrac{26}{3}+\dfrac{1}{3}\)) + (\(\dfrac{44}{7}+\dfrac{5}{7}\)) + \(\dfrac{38}{5}\)

\(\dfrac{40}{4}\) + \(\dfrac{27}{3}\) + \(\dfrac{49}{7}\) + \(\dfrac{38}{5}\)

= 10 + 9 + 7 + \(\dfrac{38}{5}\)

=26 + 7,6

= 33,6 

11 tháng 2 2023

`#lv`

`-2/5+(-7/10)-9/6`

`=-2/5-7/10-9/6`

`=-4/10-7/10-9/6`

`=-11/10-3/2`

`=-11/10-15/10`

`=-26/10`

`=-13/5`

__

`1/2+(-2/5)-(-2/3)`

`=1/2-2/5+2/3`

`=5/10-4/10+2/3`

`=1/10+2/3`

`=3/30+20/30`

`=23/30`

__

`5/3-3/4+7/6`

`=20/12-9/12+14/12`

`=11/12+14/12`

`=25/12`

__

`-1/5+5/3-3/2`

`=-3/15+25/15-3/2`

`=22/15-3/2`

`=44/30-45/30`

`=-1/30`

__

`1/4-7/8+(-9/10)`

`=2/8-7/8-9/10`

`=-5/8-9/10`

`=-25/40-36/40`

`=-61/40`

__

`5/4+1/2+(-7/12)`

`=15/12+6/12-7/12`

`=21/12-7/12`

`=14/12`

`=7/6`

__

`-5/8-1/3+(-7/6)`

`=-5/8-1/3-7/6`

`=-15/24-8/24-28/24`

`=-52/24`

`=-13/6`

__

`-3/4-7/10+(-5/6)`

`=-3/4-7/10-5/6`

`=-45/60-42/60-50/60`

`=-137/60`

11 tháng 2 2023

Bài làm

a, (-2/5) + (-7/10) - 9/6 =(-12/30) + (-21/30) - 45/30=(-33/30) - 45/30 = (-78/30)

b,1/2 + (-2/5) - (-2/3) = 15/30 + (-12/30) - (-20/30) = 3/30 - (-20/30) = 23/30

c,5/3 - 3/4 + 7/6 = 40/24 - 18/24 + 28/24 = 22/24 + 28/24 = 50/24 = 25/12

d, (-1/5) + 5/3 - 3/2 = (-6/30) + 50/30 - 45/30 = 44/30 - 45/30 = (-1/30)

e, 1/4 - 7/8 + (-9/10) = 10/40 - 35/40 - 36/40 = (-25/40) - 36/40 = (-61/40)

f, 5/4 +1/2 + (-7/12) = 15/12 + 6/12 - 7/12 = 21/12 - 7/12 = 14/127/6

g,(-5/8) -1/3 + (-7/6) = (-15/24) - 8/24 - 28/24 = (-23/24) - 28/24 = (-51/24) 

k,(-3/4) - 7/10 + (-5/6) = (-45/60) - 42/60 - 50/60 = (-87/60) - 50/60 = (-137/60)

chúc bn học tốt nha

sai thì mn góp ý giúp mk

 

20 tháng 11 2017

a) \(\left(-\dfrac{2}{3}+\dfrac{3}{7}\right):\dfrac{4}{5}+\left(-\dfrac{1}{3}+\dfrac{4}{7}\right):\dfrac{4}{5}\)

\(=\left(-\dfrac{5}{21}\right):\dfrac{4}{5}+\left(\dfrac{5}{21}\right):\dfrac{4}{5}\)

\(=\left(-\dfrac{5}{21}+\dfrac{5}{21}\right):\dfrac{4}{5}\)

\(=0:\dfrac{4}{5}\)

\(=0\)

b) \(\dfrac{5}{9}:\left(\dfrac{1}{11}-\dfrac{5}{22}\right)+\dfrac{5}{9}:\left(\dfrac{1}{15}-\dfrac{2}{3}\right)\)

\(=\dfrac{5}{9}:\left(-\dfrac{3}{22}\right)+\dfrac{5}{9}:\left(-\dfrac{3}{5}\right)\)

\(=\dfrac{5}{9}:\left[\left(-\dfrac{3}{22}\right)+\left(-\dfrac{3}{5}\right)\right]\)

\(=\dfrac{5}{9}:\left(-\dfrac{81}{110}\right)\)

\(=-\dfrac{550}{729}\)

c) \(4^2.4^3:4^{10}\)

\(=\dfrac{4^5}{4^{10}}\)

\(=\dfrac{1}{4^5}\)

\(=\dfrac{1}{256}\)

d) \(\left(0,6\right)^5:\left(0,2\right)^6\)

\(=\dfrac{\left(0,2\cdot3\right)^5}{\left(0,2\right)^6}\)

\(=\dfrac{\left(0,2\right)^5\cdot3^5}{\left(0,2\right)^6}\)

\(=\dfrac{243}{0,2}\)

\(=1215\)

Mai mốt bạn đăng một lần ít thôi nha tại giờ khuya quá nên mình chỉ làm đến đây thôi =))

15 tháng 10 2023

15 tháng 10 2023

\(a,\dfrac{4}{5}+\dfrac{1}{4}\times\dfrac{2}{5}\)

\(=\dfrac{4}{5}+\dfrac{1}{10}\)

\(=\dfrac{8}{10}+\dfrac{1}{10}\)

\(=\dfrac{9}{10}\)

\(---\)

\(b,\dfrac{7}{12}+\dfrac{3}{44}:\dfrac{3}{8}-\dfrac{1}{4}\)

\(=\left(\dfrac{7}{12}-\dfrac{1}{4}\right)+\dfrac{3}{44}\cdot\dfrac{8}{3}\)

\(=\left(\dfrac{7}{12}-\dfrac{3}{12}\right)+\dfrac{8}{44}\)

\(=\dfrac{4}{12}+\dfrac{8}{44}\)

\(=\dfrac{44}{132}+\dfrac{24}{132}\)

\(=\dfrac{68}{132}\)

\(=\dfrac{17}{33}\)

#\(Toru\)

17 tháng 9 2017

tíc cho mình nha

17 tháng 9 2017

2/3 - 7/24 = 3/8