1:

a: \(=\dfrac{-4}{7}+\dfrac{4}{7}+\dfrac{3}{7}-\dfrac{23}{34}-\dfrac{4}{5}=\dfrac{3}{7}-\dfrac{23}{34}-\dfrac{4}{5}=-\dfrac{1247}{1190}\)

b:

Sửa đề: \(\dfrac{-5}{13}+\dfrac{4}{19}+\dfrac{-8}{13}+\dfrac{15}{19}+\dfrac{45}{6}\) 

\(=\dfrac{-5}{13}-\dfrac{8}{13}+\dfrac{4}{19}+\dfrac{15}{19}+\dfrac{45}{6}=\dfrac{9}{2}\)

A

A

A

`0,75+(-1/3)-5/18`

`=3/4-1/3-5/18`

`=27/36-12/36-10/36`

`=5/36`

\(=\dfrac{3}{4}-\dfrac{1}{3}-\dfrac{5}{18}=\dfrac{27-12-10}{36}=\dfrac{5}{36}\)

`@V.Tr.V`

0.75 = 3/4 

ta có: 3/4 - 1/3 - 5/18 

= 5 / 36

\(a)x\times\dfrac{4}{7}=8\)                        \(b)\dfrac{1}{6}:x=\dfrac{5}{18}\)

\(x=8:\dfrac{4}{7}\)                                \(x=\dfrac{1}{6}:\dfrac{5}{18}\)

\(x=\dfrac{56}{4}=14\)                            \(x=\dfrac{18}{30}=\dfrac{3}{5}\)

a) x = 8 : 4/7

x = 14

b) x = 1/6 : 5/18

x = 3/5

3/5

a: =11/4+5/4-9/8

=4-9/8=32/8-9/8=23/8

b: \(=\dfrac{6}{7}\cdot\dfrac{7}{4}+\dfrac{5}{3}=\dfrac{3}{2}+\dfrac{5}{3}=\dfrac{9+10}{6}=\dfrac{19}{6}\)

c: \(=\dfrac{13}{18}\cdot\dfrac{9}{5}-1=\dfrac{13}{10}-1=\dfrac{3}{10}\)

d: \(=3+\dfrac{9}{4}\cdot\dfrac{5}{3}=3+\dfrac{45}{12}=\dfrac{81}{12}=\dfrac{27}{4}\)

`a)11/4+5/4-9/8=4-9/8=32/8-9/8=23/8`

`b)6/7 xx 7/4+5/3=3/2+5/3=9/6+10/6=19/6`

`c)13/18xx9/5−1=13/10−1=3/10`

`d)3+9/4xx5/3=3+45/12=27/4`

1) x-12=(-8)+(-17)
    x-12=(-25)
    x      = (-25)+12
    x      = (-13)

bài 1: 

\(2\dfrac{3}{4}:1\dfrac{1}{3}=\dfrac{11}{4}:\dfrac{4}{3}=\dfrac{33}{16}\)

\(\Leftrightarrow x+7=-18\)

hay x=-25

Lời giải:
a. 

$\frac{7}{4}+\frac{5}{-6}+\frac{21}{8}=\frac{42}{24}+\frac{-20}{24}+\frac{63}{24}=\frac{85}{24}$

b.

$\frac{4}{9}+\frac{-7}{12}+\frac{8}{15}$

$=\frac{80}{180}+\frac{-105}{180}+\frac{96}{180}=\frac{71}{180}$

c.

$=\frac{-1}{3}+\frac{5}{6}+\frac{19}{12}+2$
$=\frac{-4}{12}+\frac{10}{12}+\frac{19}{12}+2=\frac{25}{12}+2=\frac{49}{12}$

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