a: \(=\dfrac{-5}{8}+\dfrac{7}{12}=\dfrac{-15}{24}+\dfrac{14}{24}=\dfrac{-1}{24}\)

b: \(=\dfrac{3}{4}-\dfrac{5}{6}+\dfrac{11}{12}=\dfrac{9}{12}-\dfrac{10}{12}+\dfrac{11}{12}=\dfrac{10}{12}=\dfrac{5}{6}\)

c: \(=\dfrac{6}{36}-\dfrac{1}{36}=\dfrac{5}{36}\)

d: \(=\dfrac{5}{12}+\dfrac{5}{12}=\dfrac{10}{12}=\dfrac{5}{6}\)

e: \(=\dfrac{-8}{56}-\dfrac{7}{56}=\dfrac{-15}{56}\)

f: \(=\dfrac{-5}{15}+\dfrac{3}{25}=\dfrac{-25}{75}+\dfrac{9}{75}=\dfrac{-16}{75}\)

`#` `\text{dkhanhqlv}`

`a)1/8-1/2`

`=1/8-4/8`

`=-3/8`

`b)-11/12-(-1)`

`=-11/12+1`

`=-11/12+12/12`

`=1/12`

`c)3/5-5/6`

`=18/30-25/30`

`=-7/30`

`d)-1/16-1/15`

`=-15/240-16/240`

`=-31/240`

`e)11/36-(-7/24)`

`=11/36+7/24`

`=22/72+21/72`

`=43/72`

`g)-5/9-(-5/12)`

`=-5/9+5/12`

`=-20/36+15/36`

`=-5/36`

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

b) \(-\dfrac{11}{12}-\left(-1\right)=-\dfrac{11}{12}+\dfrac{12}{12}=\dfrac{1}{12}\)

c) \(\dfrac{3}{5}-\dfrac{5}{6}=\dfrac{18}{30}-\dfrac{25}{30}=-\dfrac{7}{30}\)

d) \(-\dfrac{1}{16}-\dfrac{1}{15}=-\dfrac{15}{240}-\dfrac{16}{240}=-\dfrac{31}{240}\)

e) \(\dfrac{11}{36}-\left(-\dfrac{7}{24}\right)=\dfrac{11}{36}+\dfrac{7}{24}=\dfrac{22}{72}+\dfrac{21}{72}=\dfrac{43}{72}\)

g) \(-\dfrac{5}{9}-\left(-\dfrac{5}{12}\right)=-\dfrac{5}{9}+\dfrac{5}{12}=-\dfrac{20}{36}+\dfrac{15}{36}=-\dfrac{5}{36}\)

\(a,\dfrac{1}{8}-\dfrac{1}{2}=\dfrac{1}{8}-\dfrac{4}{8}=-\dfrac{3}{8}\)

\(b,-\dfrac{11}{12}-\left(-1\right)=-\dfrac{11}{12}+1=-\dfrac{11}{12}+\dfrac{12}{12}=\dfrac{1}{12}\)

\(c,\dfrac{3}{5}-\dfrac{5}{6}=\dfrac{18}{30}-\dfrac{25}{30}=-\dfrac{7}{30}\)

\(d,-\dfrac{1}{16}-\dfrac{1}{15}=-\dfrac{31}{240}\)

\(e,\dfrac{11}{36}-\left(-\dfrac{7}{24}\right)=\dfrac{11}{36}+\dfrac{7}{24}=\dfrac{139}{221}\)

\(g,-\dfrac{5}{9}-\left(-\dfrac{5}{12}\right)=-\dfrac{5}{9}+\dfrac{5}{12}=-\dfrac{5}{36}\)

y:b.chac chan luon

Với câu a : \(\frac{1}{2}+\frac{1}{3}\times\frac{1}{6}=\frac{1}{2}+\frac{1}{18}=\frac{9}{18}+\frac{1}{18}=\frac{10}{18}=\frac{5}{9}\)

Ta không chọn câu a vì \(\frac{5}{9}\ne\frac{5}{36}\)khi quy đồng lên thành \(\frac{20}{36}\ne\frac{5}{36}\)

Với câu b : \(\frac{1}{9}+\frac{5}{12}-\frac{7}{18}=\frac{4}{36}+\frac{15}{36}-\frac{14}{36}=\frac{4+15-14}{36}=\frac{5}{36}\)

Ta chọn câu b vì kết quả bằng nhau theo đề bài trên

Còn các câu còn lại đều bị loại

câu b nha bạn

\(\frac{1}{2}+\frac{5}{6}+\frac{11}{12}+\frac{19}{20}+...+\frac{89}{90}\)

\(=1-\frac{1}{2}+1-\frac{1}{6}+1-\frac{1}{12}+1-\frac{1}{20}+...+1-\frac{1}{90}\)

\(=9-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{90}\right)\)

\(=9-\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{9.10}\right)\)

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

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

\(=9-\frac{9}{10}=\frac{81}{10}\)

c) Ta có: \(\dfrac{3}{5}+\dfrac{-5}{20}+\dfrac{30}{75}+\dfrac{-7}{4}\)

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

\(=1-2=-1\)

Giải:

a)-1/12+4/3=-1/12+16/12=15/12=5/4

b)(-4/14-3/15)-(1/5-20/35-(-1)).7

=-17/35-22/35.7

=-17/35-22/5

=-171/35

c)3/5+-5/20+30/75+-7/4

=3/5+-1/4+2/5+-7/4

=(3/5+2/5)+(-1/4+-7/4)

=1+-2

=-1

d)5/6.-12/14+7/13

=-5/7+7/13

=-16/91

e)2/-9-5/-36-1/4

=-1/12-1/4

=-1/3

f)2/23+-5/12+7/18+21/23+-7/12

=(2/23+21/23)+(-5/12+-7/12)+7/18

=1+-1+7/18

=7/18

xcsxccsz

\(a,\frac{3}{4}+\frac{1}{5}=\frac{15}{20}+\frac{4}{20}=\frac{19}{20}\)

\(b,\frac{1}{36}+\frac{5}{12}=\frac{1}{36}+\frac{15}{36}=\frac{16}{36}=\frac{4}{9}\)

\(c,\frac{1}{6}+\frac{3}{8}=\frac{8}{48}+\frac{18}{48}=\frac{26}{48}=\frac{13}{24}\)

\(d,\frac{1}{8}+\frac{7}{10}=\frac{10}{80}+\frac{56}{80}=\frac{66}{80}=\frac{33}{40}\)

\(e,\frac{1}{8}+\frac{5}{6}=\frac{6}{48}+\frac{40}{48}=\frac{46}{48}=\frac{23}{24}\)

\(g,\frac{2}{3}+\frac{2}{7}=\frac{14}{21}+\frac{6}{21}=\frac{20}{21}\)

như bạn roronoa vừa làm

a) \(\frac{3}{4}+\frac{1}{5}=\frac{15}{20}+\frac{4}{20}=\frac{19}{20}\)

b) \(\frac{1}{36}+\frac{5}{12}=\frac{1}{36}+\frac{15}{36}=\frac{16}{36}=\frac{4}{9}\)

c) \(\frac{1}{6}+\frac{3}{8}=\frac{4}{24}+\frac{9}{24}=\frac{13}{24}\)

d) \(\frac{1}{8}+\frac{7}{10}=\frac{10}{80}+\frac{56}{80}=\frac{66}{80}=\frac{33}{40}\)

e) \(\frac{1}{8}+\frac{5}{6}=\frac{3}{24}+\frac{20}{24}=\frac{23}{24}\)

g) \(\frac{2}{3}+\frac{2}{7}=\frac{14}{21}+\frac{6}{21}=\frac{20}{21}\)

a) \(\frac{1}{4}-\frac{3}{5}+\frac{75}{100}\)

     = 

Giúp mình bài này nhé mình sẽ tích cho bạn

Mình đi ngủ chút bạn giải jup nhé

\(A=\dfrac{7}{12}+\dfrac{5}{12}:6-\dfrac{11}{36}=\dfrac{21}{36}+\dfrac{5}{12}.\dfrac{1}{6}-\dfrac{11}{36}=\dfrac{5}{18}+\dfrac{5}{12}.\dfrac{1}{6}=\dfrac{20}{72}+\dfrac{5}{72}=\dfrac{25}{72}\)

\(B=1\dfrac{3}{8}+\dfrac{1}{8}:\left(0,75-\dfrac{1}{2}\right)-25\%.\dfrac{1}{2}=\dfrac{11}{8}+\dfrac{1}{8}:\dfrac{1}{4}-\dfrac{1}{8}=\dfrac{5}{4}+\dfrac{1}{2}=\dfrac{7}{4}\)

A. 25/72

B. 7/4

a) Ta có: \(A=\dfrac{7}{12}+\dfrac{5}{12}:6-\dfrac{11}{36}\)

\(=\dfrac{7}{12}+\dfrac{5}{72}-\dfrac{11}{36}\)

\(=\dfrac{42+5-22}{72}\)

\(=\dfrac{25}{72}\)

b) Ta có: \(A=1\dfrac{3}{8}+\dfrac{1}{8}:\left(0.75-\dfrac{1}{2}\right)-25\%\cdot\dfrac{1}{2}\)

\(=\dfrac{11}{8}+\dfrac{1}{8}:\dfrac{1}{4}-\dfrac{1}{4}\cdot\dfrac{1}{2}\)

\(=\dfrac{11}{8}-\dfrac{1}{8}+\dfrac{1}{2}\)

\(=\dfrac{10}{8}+\dfrac{1}{2}\)

\(=\dfrac{5}{4}+\dfrac{2}{4}=\dfrac{7}{4}\)

giúp nhanh ạ, mình cần gấp

Bài 5:

a: =1/3+2/5

=5/15+6/15

=11/15

b: =6/21+12/21=18/21=6/7

c: =16/24+10/24

=26/24

=13/12

d: =4/12+3/12+10/12

=17/12

e: =19/24-9/24

=10/24

=5/12

f: =8/9-3/9=5/9

g: =9/3+1/3=10/3

k: =15/24+42/24+14/24

=71/24