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LM
Lê Minh Vũ
CTVHS VIP
25 tháng 6 2023

\(\dfrac{7}{38}-\dfrac{8}{-9}+\dfrac{2}{-9}\)

\(=\dfrac{7}{38}-\dfrac{-8}{9}+\dfrac{-2}{9}\)

\(=\dfrac{7}{38}+\dfrac{8}{9}-\dfrac{2}{9}\)

\(=\dfrac{367}{342}-\dfrac{2}{9}\)

\(=\dfrac{97}{114}\)

25 tháng 6 2023

Bai de ko bt ngu vai

 

 

12 tháng 3 2023

`4/7 x -x=-9/14`

`=> 4/7 x - x . 1 =-9/14`

`=> (4/7-1) x=-9/14`

`=> -3/7 x=-9/14`

`=>x=-9/14 : (-3/7)`

`=>x=-9/14 xx (-7/3)`

`=>x=3/2`

a) Ta có: \(\dfrac{39}{-65}=\dfrac{-39}{65}=\dfrac{-39:13}{65:13}=\dfrac{-3}{5}\)

\(\dfrac{-3}{5}=\dfrac{-3}{5}\)

Do đó: \(\dfrac{-3}{5}=\dfrac{39}{-65}\)

b) Ta có: \(\dfrac{-9}{27}=\dfrac{-9:9}{27:9}=\dfrac{-1}{3}\)

\(\dfrac{-41}{123}=\dfrac{-41:41}{123:41}=\dfrac{-1}{3}\)

Do đó: \(\dfrac{-9}{27}=\dfrac{-41}{123}\)

c) Ta có: \(\dfrac{-3}{4}=\dfrac{-3\cdot5}{4\cdot5}=\dfrac{-15}{20}\)

\(\dfrac{4}{-5}=\dfrac{-4}{5}=\dfrac{-4\cdot4}{5\cdot4}=\dfrac{-16}{20}\)

mà \(\dfrac{-15}{20}>\dfrac{-16}{20}\)

nên \(\dfrac{-3}{4}>\dfrac{4}{-5}\)

d) Ta có: \(\dfrac{2}{-3}=\dfrac{-2}{3}=\dfrac{-2\cdot7}{3\cdot7}=\dfrac{-14}{21}\)

\(\dfrac{-5}{7}=\dfrac{-5\cdot3}{7\cdot3}=\dfrac{-15}{21}\)

mà \(\dfrac{-14}{21}>\dfrac{-15}{21}\)

nên \(\dfrac{2}{-3}>\dfrac{-5}{7}\)

18 tháng 4 2021

a) \(\dfrac{5}{9}:\left(\dfrac{13}{7}+\dfrac{13}{9}\right)-\dfrac{5}{3}\)(chỗ này mk lười chép lại đề)

=\(\dfrac{5}{9}:\dfrac{208}{63}-\dfrac{5}{3}\)

=\(\dfrac{5}{9}.\dfrac{63}{208}-\dfrac{5}{3}\)

=\(\dfrac{5.63}{9.208}-\dfrac{5}{3}\)

=\(\dfrac{5.7}{1.208}-\dfrac{5}{3}\)

=\(\dfrac{36}{208}-\dfrac{5}{3}\)

=\(\dfrac{108}{624}-\dfrac{1040}{624}\)

=\(\dfrac{-932}{624}\)

=\(\dfrac{233}{156}\)

                                 còn câu b mk chưa học nên mk chịu

 

Giải:

5/9:13/7+5/9:13/9 -1 2/3

=5/9.7/13+5/9.9/13-5/3

=5/9.(7/13+9/13)-5/3

=5/9.16/13-5/3

=80/117-5/3

=-115/117

4 2/5 : 0,5% -1 3/7 .14% +(-0,5)

=22/5:1/200-10/7.7/50 +(-1/2)

=880-1/5-1/2

=8793/10

1 tháng 4 2021

\(\dfrac{2}{3}+\dfrac{1}{5}.\dfrac{10}{7}=\dfrac{2}{3}+\dfrac{10}{35}=\dfrac{70}{105}+\dfrac{30}{105}=\dfrac{100}{105}=\dfrac{50}{21}\)

a) Ta có: \(\dfrac{2}{3}+\dfrac{1}{5}\cdot\dfrac{10}{7}\)

\(=\dfrac{2}{3}+\dfrac{2}{7}\)

\(=\dfrac{14}{21}+\dfrac{6}{21}\)

\(=\dfrac{20}{21}\)

8: \(=\dfrac{-5}{9}-\dfrac{4}{9}+\dfrac{8}{15}+\dfrac{7}{15}-\dfrac{2}{11}=\dfrac{-2}{11}\)

9: =2/7-2/5+5/7=1-2/5=3/5

10: \(=\dfrac{7}{19}\left(\dfrac{8}{11}+\dfrac{3}{11}\right)-\dfrac{12}{19}=\dfrac{-5}{19}\)

11: \(=\dfrac{-5}{7}\left(\dfrac{2}{11}+\dfrac{9}{11}\right)=\dfrac{-5}{7}\)

16 tháng 4 2022

8 = -2/11

9 = 3/5

10 = -5/19

11 = -5/7

11 = 5/13

 

 

12 tháng 7 2021

a)A=\(\left(\dfrac{1}{3}-\dfrac{1}{3}\right)+\left(\dfrac{-3}{5}+\dfrac{3}{5}\right)+\left(\dfrac{5}{7}-\dfrac{5}{7}\right)+\left(\dfrac{-7}{9}+\dfrac{7}{9}\right)+\left(\dfrac{9}{11}-\dfrac{9}{11}\right)+\left(\dfrac{-11}{13}+\dfrac{11}{13}\right)+\dfrac{13}{15}\)

A=0+0+0+...+0+\(\dfrac{13}{15}\)

A=\(\dfrac{13}{15}\)

b) Ta có: \(-\dfrac{1}{9\cdot10}-\dfrac{1}{8\cdot9}-\dfrac{1}{7\cdot8}-...-\dfrac{1}{2\cdot3}-\dfrac{1}{1\cdot2}\)

\(=-\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{4}-\dfrac{1}{4}+...+\dfrac{1}{9}-\dfrac{1}{10}\right)\)

\(=-\left(1-\dfrac{1}{10}\right)=\dfrac{-9}{10}\)

AH
Akai Haruma
Giáo viên
17 tháng 4 2023

Lời giải:
a.

$x=\frac{-5}{6}-\frac{2}{3}=\frac{-3}{2}$

b.

$\frac{2}{3}x=\frac{1}{10}-\frac{1}{2}=\frac{-2}{5}$

$x=\frac{-2}{5}: \frac{2}{3}=\frac{-3}{5}$

c.

$\frac{7}{8}x=\frac{2}{9}-\frac{1}{3}=\frac{-1}{9}$
$x=\frac{-1}{9}: \frac{7}{8}=\frac{-8}{63}$

 

 

AH
Akai Haruma
Giáo viên
17 tháng 4 2023

d.

$\frac{5}{7}: x=\frac{1}{6}-\frac{4}{5}=\frac{-19}{30}$

$x=\frac{5}{7}: \frac{-19}{30}=\frac{-150}{133}$

e.

$(\frac{2}{5}-1\frac{2}{3}):x=\frac{2}{5}+\frac{3}{5}=1$

$\frac{-19}{15}: x=1$

$x=\frac{-19}{15}:1 =\frac{-19}{15}$

f.

$(-\frac{3}{4}+x).2\frac{2}{3}=1$

$\frac{-3}{4}+x=1: 2\frac{2}{3}=\frac{3}{8}$

$x=\frac{3}{8}+\frac{3}{4}=\frac{9}{8}$

7 tháng 2 2023

`6/7 . 8/13 +6/7 . 9/13+3/13 . 6/7`

`=6/7 . (8/13+9/13+3/13)`

`=6/7 . 20/13`

`=120/91`

7 tháng 2 2023

\(\dfrac{6}{7}.\dfrac{8}{13}+\dfrac{6}{7}.\dfrac{9}{13}+\dfrac{3}{13}.\dfrac{6}{7}\)

\(=\dfrac{6}{7}.\left(\dfrac{8}{13}+\dfrac{9}{13}+\dfrac{3}{13}\right)\)

\(=\dfrac{6}{7}.\left(\dfrac{8+9+3}{13}\right)\)

\(=\dfrac{6}{7}.\dfrac{20}{13}\)

\(=\dfrac{6.20}{7.13}\)

\(=\dfrac{120}{91}\)

   \(\dfrac{3}{7}.\dfrac{5}{9}+\dfrac{4}{9}.\dfrac{-3}{7}+\left(-2023^0\right)\)

\(=\left(\dfrac{3}{7}.\dfrac{5}{9}\right)+\left(\dfrac{4}{9}.\dfrac{-3}{7}\right)+\left(-1\right)\)

\(=\dfrac{5}{21}+\dfrac{-4}{21}+\left(-1\right)\)

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

\(=\dfrac{5-4-21}{21}=\dfrac{-20}{21}\)