Bài 1:

a: \(x=\dfrac{2}{3}:\dfrac{3}{5}=\dfrac{2}{3}\cdot\dfrac{5}{3}=\dfrac{10}{9}\)

b: \(x=\dfrac{17}{8}:\dfrac{7}{17}=\dfrac{17}{8}\cdot\dfrac{17}{7}=\dfrac{289}{56}\)

c: \(x=-\dfrac{3}{4}:\dfrac{7}{12}=\dfrac{-3}{4}\cdot\dfrac{12}{7}=\dfrac{-63}{28}=-\dfrac{9}{4}\)

d: \(\Leftrightarrow x\cdot\dfrac{1}{6}=\dfrac{3}{8}-\dfrac{1}{4}=\dfrac{1}{4}\)

hay \(x=\dfrac{1}{4}:\dfrac{1}{6}=\dfrac{3}{2}\)

e: \(\Leftrightarrow\dfrac{1}{2}:x=-4-\dfrac{1}{3}=-\dfrac{17}{3}\)

hay \(x=-\dfrac{1}{2}:\dfrac{17}{3}=\dfrac{-3}{34}\)

dad

1+2+3+4+5+6+7+8+9+10+11+12+13-1-2-3-4-5-6-7-8-9-10-11-12

=(1-1)+(2-2)+(3-3)+(4-4)+(5-5)+(6-6)+(7-7)+(8-8)+(9-9)+(10-10)+(11-11)+(12-12)+13

=  0  +  0  +  0  +  0  +   0  +  0  +  0  +  0  +  0  + 0  + 0   +  0  +  13

=                                 13

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 - 1 - 2 - 3 - 4 - 5 - 6 - 7- 8 - 9 - 10 

= (1+12) + (2+11) + (3+10) + ( 4+9) + (5+8) + (6+7) + 13 -  (1+11) - ( 2+10) - ( 3+9) - (4+8) - (5+7) + 6 + 12

= 13 * 7 - 12 * 6 + 6

= 13

Ai k mk mk k lại

= 13 nhé hihi nha

ai giúp đi

a ) \(\frac{3}{4}\)+ \(\frac{1}{6}\) = \(\frac{18}{24}\)+  \(\frac{4}{24}\)=  \(\frac{22}{24}\)

b ) \(\frac{11}{12}\)-  \(\frac{3}{4}\)= \(\frac{11}{12}\)- \(\frac{9}{12}\)= \(\frac{2}{12}\)

c ) \(\frac{11}{12}\)- \(\frac{1}{6}\) = \(\frac{11}{12}\)- \(\frac{2}{12}\) = \(\frac{9}{12}\)

d ) \(\frac{1}{6}\)+ \(\frac{3}{4}\)= \(\frac{4}{24}\)+ \(\frac{18}{24}\)   = \(\frac{22}{24}\)

Xin lỗi mình không rút gọn nha !

a,3/4+1/6=18/24+4/24=22/24

b,11/12-3/4=11/12-9/12=2/12

c,11/12-1/6=11/12-2/12=9/12

d,1/6+3/4=4/24+18/24=22/24

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

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

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

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

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

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

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

dễ nhưng ko tính

a: =5/6(-12/7)-1/2=-10/7-1/2=-27/14

b: =11/9(-6/5+1/5)=-11/9

coi lại câu a

1.1+1.1+1.1+1.1+1.1/1.1+1.1+9.3+6.8+.2