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29 tháng 5 2022

a) \(\dfrac{-2}{3}+\dfrac{3}{4}=\dfrac{-8}{12}+\dfrac{9}{12}=\dfrac{1}{12}\)

b) \(\dfrac{5}{6}-\dfrac{-3}{5}=\dfrac{5}{6}+\dfrac{3}{5}=\dfrac{25}{30}+\dfrac{18}{30}=\dfrac{43}{30}\)

29 tháng 5 2022

`a)` \(\dfrac{-2}{3}+\dfrac{3}{4}=\dfrac{-8}{12}+\dfrac{9}{12}=\dfrac{1}{12}\)

`b)` \(\dfrac{5}{6}-\dfrac{-3}{5}=\dfrac{5}{6}+\dfrac{3}{5}=\dfrac{25}{30}+\dfrac{18}{30}=\dfrac{43}{30}\)

6 tháng 9 2021

A = (\(\dfrac{5}{6}\) - \(\dfrac{4}{5}\)) . 1\(\dfrac{1}{5}\) + \(\dfrac{3}{16}\) : (\(\dfrac{-1}{2}\))3

A = \(\dfrac{1}{30}\) . \(\dfrac{6}{5}\) + \(\dfrac{3}{16}\) : \(\dfrac{-1}{8}\)

A = \(\dfrac{1}{25}\) + \(\dfrac{3}{16}\) . \(\dfrac{-8}{1}\)

A = \(\dfrac{1}{25}\) + \(\dfrac{-3}{2}\)

A = \(\dfrac{-73}{50}\)

6 tháng 9 2021

B = \(\dfrac{4}{17}\) . (7\(\dfrac{3}{4}\) - 6\(\dfrac{1}{3}\)) + (5\(\dfrac{3}{4}\) - 6.95) : (-1\(\dfrac{3}{5}\))

B = \(\dfrac{4}{17}\) . \(\dfrac{17}{12}\) + (\(\dfrac{23}{4}\) - \(\dfrac{139}{20}\)) : \(\dfrac{-8}{5}\)

B = \(\dfrac{1}{3}\) + \(\dfrac{-6}{5}\) . \(\dfrac{-5}{8}\)

B = \(\dfrac{13}{12}\)

2:

a: =>2/3:x=1,4-2,4=-1

=>x=-2/3

b: =>x/5=25/30-19/30=6/30=1/5

=>x=1

3:

Số học sinh giỏi là 40*1/4=10 bạn

Số học sinh khá là 30*3/5=18 bạn

Số học sinh TB là 30-18=12 bạn

 

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

\(=\dfrac{-3}{6}+\dfrac{5}{6}+\dfrac{2}{6}\)

\(=\dfrac{4}{6}=\dfrac{2}{3}\)

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

\(=\dfrac{-9}{24}+\dfrac{42}{24}-\dfrac{2}{24}\)

\(=\dfrac{31}{24}\)

c: \(\dfrac{3}{5}:\left(\dfrac{1}{4}\cdot\dfrac{7}{5}\right)=\dfrac{3}{4}:\dfrac{7}{20}=\dfrac{3}{4}\cdot\dfrac{20}{7}=\dfrac{15}{7}\)

d: \(\dfrac{10}{11}+\dfrac{4}{11}:4-\dfrac{1}{8}\)

\(=\dfrac{10}{11}+\dfrac{1}{11}-\dfrac{1}{8}=\dfrac{7}{8}\)

31 tháng 8 2021

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5 tháng 5 2021

a) \(\dfrac{-4}{6}\)

b) \(\dfrac{1}{3}\)-\(\dfrac{20}{60}\)

= 0 

c) \(-20^2\)+(\(-50^3\))

= -400 + (-125000)

=-125400

d) \(\dfrac{-2}{7}\)+\(\dfrac{15}{35}\)

\(\dfrac{-10}{35}\)+\(\dfrac{15}{35}\)

\(\dfrac{5}{35}\)=\(\dfrac{1}{7}\)

5 tháng 5 2021

Nhớ tick cho mk nha

a) \(A=\dfrac{3}{5}+6\dfrac{5}{6}+\left(11\dfrac{5}{20}-9\dfrac{1}{4}\right):8\dfrac{1}{3}\)

\(=\dfrac{3}{5}+\dfrac{41}{6}\left(11\dfrac{1}{4}-9\dfrac{1}{4}\right):8\dfrac{1}{3}\)

\(=\dfrac{3}{5}+\dfrac{41}{6}.2.\dfrac{3}{25}\)

\(=\dfrac{3}{5}+\dfrac{41}{25}\)

\(=\dfrac{15}{25}+\dfrac{41}{25}\)

\(=\dfrac{56}{25}\)

16 tháng 4 2021

a) A = \(\dfrac{3}{5}+6\dfrac{5}{6}\left(11\dfrac{5}{20}-9\dfrac{1}{4}\right):8\dfrac{1}{3}\) 

A = \(\dfrac{3}{5}+\dfrac{41}{6}\) \(\left(\dfrac{45}{4}-\dfrac{37}{4}\right)\) : \(\dfrac{25}{3}\) 

A = \(\dfrac{3}{5}+\dfrac{41}{6}\)  . 2 : \(\dfrac{25}{3}\) 

A = \(\dfrac{3}{5}\) + \(\dfrac{41}{3}\) : \(\dfrac{25}{3}\) 

A = \(\dfrac{3}{5}\)  + \(\dfrac{41}{25}\) 

A = \(\dfrac{56}{25}\)

a: \(=\dfrac{-7}{8}\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+3+\dfrac{7}{8}=\dfrac{-7}{8}+\dfrac{7}{8}+3=3\)

b: \(=-\dfrac{8}{5}:\dfrac{5}{3}=-\dfrac{24}{25}\)

c: \(=\dfrac{6}{7}+\dfrac{1}{8}-\dfrac{3}{4}=\dfrac{6}{7}+\dfrac{1}{8}-\dfrac{6}{8}=\dfrac{6}{7}-\dfrac{5}{8}=\dfrac{48}{56}-\dfrac{35}{56}=\dfrac{13}{56}\)

 

9 tháng 6 2021

a) `(5^4 . 20^4)/(25^3 .4^5)`

`=(5^4 . (5.4)^4)/((5^2)^3 .4^5)`

`= (5^4 . 5^4 . 4^4)/(5^6 . 4^5)`

`= (5^2)/4=25/4`

b) `(-10/3)^5 . (-6/5)^4`

`=-10/3 . [(-10/3) . (-6/5)]^4`

`= -10/3 . [ (-5.2 . (-2).3)/(3.5)]^4`

`=-10/3 . 4^4`

`=-2560/3`

9 tháng 6 2021

A) \(=\dfrac{\left(5.20\right)^4}{\left(25.4\right)^5}=\dfrac{100^4}{100^5}=\dfrac{1}{100}\)

B)=\(\left(\dfrac{-10}{3}\right).\left(\dfrac{-10}{3}\right)^4.\left(\dfrac{-6}{5}\right)^4\)

   =\(\left(\dfrac{-10}{3}\right).\left(\dfrac{-10}{3}.\dfrac{-6}{5}\right)^4\)

   =\(\left(\dfrac{-10}{3}\right).\left(\dfrac{60}{15}\right)^4\)

   =\(\left(\dfrac{-10}{3}\right).4^4\)

   =\(\left(\dfrac{-10}{3}\right).256\)

   =\(\dfrac{-2650}{3}\)