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4 tháng 8 2018

Ta có : a, 25/7 + 13/21 - 11/7 + 17/21 + 1/3 .

= ( 25/7 - 11/7 ) + ( 13/21 + 17/21 + 1/3 ) .

= 2 + ( 20/21 + 7/21 ) .

= 2 + 9/7 .

= 23/7 .

b, ( 1/3 + 12/67 + 13/41 ) - ( 79/67 - 28/41 ) .

= 1/3 + 12/67 + 13/41 - 79/67 + 28/41 .

= 1/3 + ( 12/67 - 79/67 ) + ( 13/41 + 28/41 ) .

= 1/3 - 1 + 1 .

= 1/3 .

c, ( 11/4 . -5/9 - 4/9 . 11/4 ) . 8/33 .

= [ 11/4 . ( -5/9 - 4/9 ) ] . 8/33 .

= [ 11/4 . ( - 1 ) ] . 8/33 .

= -11/4 . 8/33 .

= -2/3 .

d, 38/45 - ( 8/45 - 17/51 - 3/11 ) .

= 38/45 - 8/45 + 17/51 + 3/11 .

= 2/3 + 17/51 + 3/11 .

= 374/561 + 187/561 + 153/561 .

= 14/11 .

29 tháng 7 2018

A)0,25:(10,3-9,8)-3/4

=1/4:(103/10-49/5)-3/4

=1/4:1/2-3/4

=1/2-3/4

=2/4-3/4

=-1/4

B)-5/9.13/28-13/28.4/9

=-5/9-4/9.13/28

=-1.13/28

=-13/28

c)6/7+5/8:5-3/16

=6/7+1/8-3/16

=55/56-3/16

=89/112

d)-5/7.2/11+-5/7.9/11+1/5/7

=-5/7.(2/11+9/11)+12/7

=-5/7.1+12/7

=-5/7+12/7

=1

e)-7/12-8/15+11/20

=-67/60+11/20

=-17/30

f)-17/25.20/33+-17/25.13/33+-3/25

=-17/25.(20/33+13/33)-3/25

=-17/25.1-3/25

=-17/25-3/25

=-4/5

CHÚC BẠN HỌC TỐT...............

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21 tháng 6 2017

a) \(1\dfrac{4}{23}+\dfrac{5}{21}-\dfrac{4}{23}+0,5+\dfrac{16}{21}=\left(1\dfrac{4}{23}-\dfrac{4}{23}\right)+\left(\dfrac{5}{21}+\dfrac{16}{21}\right)+0,5=1+1+0,5=2,5\)b)

\(\dfrac{3}{7}.19\dfrac{1}{3}-\dfrac{7}{7}.33\dfrac{1}{3}=\dfrac{7}{3}\left(19\dfrac{1}{3}-33\dfrac{1}{3}\right)=\dfrac{7}{3}.\left(-14\right)=-\dfrac{1}{6}\)

c,

\(\left(15\dfrac{1}{4}+2010\right):\left(-\dfrac{5}{7}\right)-\left(25\dfrac{1}{4}+2016\right):\left(\dfrac{-5}{7}\right)=\left(15\dfrac{1}{4}+2010\right):\left(-\dfrac{7}{5}\right)-\left(25\dfrac{1}{4}+2016\right):\left(\dfrac{-7}{5}\right)\)

\(\left(-\dfrac{7}{5}\right)\left(15\dfrac{1}{4}+2010-25\dfrac{1}{4}-2016\right)=\left(-\dfrac{7}{5}\right)\left(-10-6\right)=22,4\)

d,

\(\left(2017-\dfrac{3}{7}+\dfrac{9}{11}\right)-\left(2016-\dfrac{3}{7}+\dfrac{8}{17}\right)-\left(2015+\dfrac{9}{11}-\dfrac{8}{17}\right)=2017-\dfrac{3}{7}+\dfrac{9}{11}-2016+\dfrac{3}{7}-\dfrac{8}{17}-2015-\dfrac{9}{11}+\dfrac{8}{17}\)\(\left(2017-2016-2015\right)+\left(-\dfrac{3}{7}+\dfrac{3}{7}\right)+\left(\dfrac{9}{11}-\dfrac{9}{11}\right)+\left(-\dfrac{8}{17}+\dfrac{8}{17}\right)=-2014\)

22 tháng 6 2017

Bạn ơi cho mình hỏi tại sao đề bài câu c là -5/7 mà bn lm -7/5

9 tháng 11 2018

a.\(\dfrac{17}{15}\div\dfrac{4}{3}=\dfrac{17}{20}\)

b.\(\dfrac{-12}{21}\div\dfrac{34}{43}=\dfrac{-86}{119}\)

c.\(\dfrac{-5}{9}\times\dfrac{3}{11}+\dfrac{13}{18}\times\dfrac{3}{11}\)

=\(\dfrac{3}{11}\times(\dfrac{-5}{9}+\dfrac{13}{18})=\dfrac{3}{11}\times\dfrac{1}{6}=\dfrac{1}{22}\)

d.\(\dfrac{-2}{9}\times\dfrac{5}{11}+\dfrac{-16}{9}\times\dfrac{5}{11}=\dfrac{5}{11}\times(\dfrac{-2}{9}+\dfrac{-16}{9})\)

=\(\dfrac{5}{11}\times(-2)=\dfrac{-10}{11}\)

19 tháng 12 2017

Mình chỉ cho đáp án thôi,sai thì châm chước cho mìn nha!

a)-91 phần200

b)-25phần 4

c)5 phần 2

d)2

e)0

24 tháng 12 2017

a, ( 0,36-2,18) : ( 3,8 + 0,2)

= -1,82 : 4

=-0,455 hay -91/200

b, 3/8*19/1/3-3/8*33/1/3

=3/8*(19/1/3-33/1/3)

=3/8*(-14)

=-21/4

11 tháng 11 2018

a)= \(\left(\dfrac{4}{9}-\dfrac{17}{18}\right)+\left(\dfrac{17}{14}-\dfrac{5}{7}\right)+\dfrac{11}{125}\)

= \(\dfrac{-1}{2}\) + \(\dfrac{1}{2}\) + \(\dfrac{11}{125}\)

= 0 + \(\dfrac{11}{125}\)

= \(\dfrac{11}{125}\)

b) \(=\left(1-1\right)+\left(\dfrac{-1}{2}-\dfrac{1}{2}\right)+\left(2-2\right)\) +

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

= 0 + (-1) + 0 + (-1) + 0 + (-1) + 4

= -1

c) = \(\dfrac{1}{3}.\dfrac{14}{25}-\dfrac{1}{2}.\dfrac{14}{25}\)

= \(\dfrac{14}{25}.\left(\dfrac{1}{3}-\dfrac{1}{2}\right)\)

= \(\dfrac{14}{25}.\left(\dfrac{-1}{6}\right)\)

= \(\dfrac{-7}{75}\)

d) = \(\left(\dfrac{3}{7}+\dfrac{4}{7}\right)+\left(\dfrac{5}{13}-\dfrac{18}{13}\right)\)

= 1 + (-1)

= 0

21 tháng 10 2017

a. \(\dfrac{11}{24}-\dfrac{5}{41}+\dfrac{13}{24}+0,5-\dfrac{36}{41}\)

\(=\left(\dfrac{11}{24}+\dfrac{13}{24}\right)+\left(\dfrac{-5}{41}-\dfrac{36}{41}\right)+0,5\)

\(=1+\left(-1\right)+0,5\)

\(=0,5\)

b. \(-12:\left(\dfrac{3}{4}-\dfrac{5}{6}\right)^2\)

\(=-12:\left(\dfrac{-1}{12}\right)^2\)

\(=-12:\dfrac{1}{144}\)

\(=-1728\)

c. \(\dfrac{7}{23}.\left[\left(-\dfrac{8}{6}\right)-\dfrac{45}{18}\right]\)

\(=\dfrac{7}{23}.\dfrac{-23}{6}\)

\(=\dfrac{-7}{6}\)

d. \(23\dfrac{1}{4}.\dfrac{7}{5}-13\dfrac{1}{4}:\dfrac{5}{7}\)

\(=23\dfrac{1}{4}.\dfrac{7}{5}-13\dfrac{1}{4}.\dfrac{7}{5}\)

\(=\left(23\dfrac{1}{4}-13\dfrac{1}{4}\right).\dfrac{7}{5}\)

\(=10.\dfrac{7}{5}\)

\(=14\)

e. \(\left(1+\dfrac{2}{3}-\dfrac{1}{4}\right).\left(0,8-\dfrac{3}{4}\right)^2\)

\(=\dfrac{17}{12}.\left(\dfrac{1}{20}\right)^2\)

\(=\dfrac{17}{12}.\dfrac{1}{400}=\dfrac{17}{4800}\)

19 tháng 6 2018

8)\(\frac{4}{9}:\left(-\frac{1}{7}\right)+6\frac{5}{9}:\left(-\frac{1}{7}\right)\)

=\(\frac{4}{9}:\left(-\frac{1}{7}\right)+\frac{59}{9}:\left(-\frac{1}{7}\right)\)

=\(\left(\frac{4}{9}+\frac{59}{9}\right).\left(-7\right)\)

=7.(-7)

=-49