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`f)(-2)/17 + 15/23 + (-15)/17 + 4/19 + 8/23`
`= (-2/17+ -15/17)+(15/23+8/23)+4/19`
`= -1+1+4/19`
`= 0 +4/19`
`= 0`
`g)(-1)/2 + 3/21 + (-2)/6 + (-5)/30`
`= (-1)/2 + 1/7 + (-1)/3 + (-1)/6`
`= (-21)/42 + 6/42 + (-14)/42 + (-7)/42`
`=(-36)/42`
`=(-6)/7`
f)\(-\dfrac{2}{17}+\dfrac{15}{23}+-\dfrac{15}{17}+\dfrac{4}{19}+\dfrac{8}{23}\)
\(=\left(-\dfrac{2}{17}+-\dfrac{15}{17}\right)+\left(\dfrac{15}{23}+\dfrac{8}{23}\right)+\dfrac{4}{19}\)
\(=-1+1+\dfrac{4}{19}\)
\(=0+\dfrac{4}{19}=\dfrac{4}{19}\)
g)\(-\dfrac{1}{2}+\dfrac{3}{21}+-\dfrac{2}{6}+-\dfrac{5}{30}\)
\(=-\dfrac{1}{2}+\dfrac{1}{7}+-\dfrac{1}{3}+-\dfrac{1}{6}\)
\(=\left(-\dfrac{1}{2}+-\dfrac{1}{3}+-\dfrac{1}{6}\right)+\dfrac{1}{7}\)
\(=-\dfrac{3+2+1}{6}+\dfrac{1}{7}\)
\(=\dfrac{1}{7}-1\)
\(=\dfrac{1}{7}-\dfrac{7}{7}=-\dfrac{6}{7}\)
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a) Ta có: \(\dfrac{21}{25}\cdot\dfrac{11}{9}\cdot\dfrac{5}{7}\)
\(=\dfrac{21\cdot11\cdot5}{25\cdot9\cdot7}\)
\(=\dfrac{3\cdot7\cdot11\cdot5}{5\cdot5\cdot3\cdot3\cdot7}\)
\(=\dfrac{11}{5\cdot3}=\dfrac{11}{15}\)
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a ) \(-\frac{13}{30}+\frac{11}{20}-\frac{7}{15}\)
\(=-\frac{26}{60}+\frac{33}{60}-\frac{28}{60}\)
\(=\frac{-26+33-28}{60}=-\frac{7}{20}\)
b ) \(-\frac{5}{72}:\left(\frac{3}{8}.\frac{7}{9}\right)\)
\(=-\frac{5}{72}:\frac{3.7}{8.9}\)
\(=-\frac{5}{72}:\frac{7}{24}\)
\(=-\frac{5}{72}.\frac{24}{7}=-\frac{5}{21}\)
a) \(\frac{-13}{30}+\frac{11}{20}-\frac{7}{15}=\frac{-26}{60}+\frac{33}{60}-\frac{28}{60}=-\frac{21}{60}=-\frac{7}{20}\)
b) \(\frac{-5}{72}:\left(\frac{3}{8}.\frac{7}{9}\right)=\frac{-5}{72}:\frac{7}{24}=-\frac{5}{21}\)
c) \(\frac{-23}{25}.\frac{10}{13}+\frac{-23}{25}.\frac{3}{13}+\frac{-27}{25}\)
\(=\frac{-23}{25}.\left(\frac{10}{13}+\frac{3}{13}\right)+\frac{-27}{25}\)
\(=\frac{-23}{25}+\frac{-27}{25}\)
\(=\frac{-50}{25}=-2\)
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a) -x +8=-17-30
-x+8+17+30=0
-x+55=0
-x=-55
x=55
b) 35-x=37
x=-2
c)(-19-x)+23=-20
-19-x+23+20=0
24-x=0
x=24
d) ( x-45):2=-17
x-45=-34
x=11
a) -x + 8 = -17 - 30
-x + 8 = -47
-x = -47 - 8
-x = -55
=> x = 55
Vậy x = 55
b) 35 - x = 37
x = 35 - 37
x = -2
Vậy x = -2
c)( -19 - x) + 23 = -20
(-19 - x) = -20 - 23
-19 - x = -43
x = -19 - (-43)
x = 24
Vậy x - 24
d)(x - 45) : 2 = -17
x - 45 = -17 . 2
x - 45 = -34
x = -34 + 45
x = 11
Vậy x = 11
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(\(\frac{121}{122}\). \(\frac{123}{125}\)) .(\(\frac{1995}{1996}\).\(\frac{17}{16}\)- \(\frac{21}{25}\):\(\frac{16}{17}\)).(\(\frac{42}{30}\).\(\frac{75}{23}\)-\(\frac{19}{23}\).\(\frac{210}{38}\))
= (121/122 . 123/125) . ( 1995/1996 . 17/16 - 21/25 : 16/ 17) . 0
= 0
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![](https://rs.olm.vn/images/avt/0.png?1311)
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a/ -x + 8 = -17-30
-x + 8 = -47
-x = -47 - 8
-x = -55
x = 55
Vậy x = 55
b/ 35 – x = 37
x = 35 - 37
x = -2
Vậy x = -2
c/ (-19 – x) + 23 = -20
-19 – x = -20 - 23
-19 – x = -43
x = -19 - (-43)
x = 24
Vậy x = 24
d/ (x – 45) : 2 = -17
x – 45 = -17 * 2
x – 45 = -34
x = -34 + 45
x = 11
Vậy x = 11
a/ -x + 8 = -17-30
-x + 8 = -47
-x =-47 - 8
-x = -55
x = 55
Vậy x = 55
Phần a mình bị lỗi nên sửa lại nha
=(-40)+(-30)
=(-70)
HT
-70 nha bn
@Mina
#hoangphuong