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\(\left(\dfrac{-5}{28}+1,75+\dfrac{8}{35}\right)\):\(\left(\dfrac{-39}{20}\right)\)
=\(\left(\dfrac{-5}{28}+\dfrac{7}{4}+\dfrac{8}{35}\right):\left(\dfrac{-39}{20}\right)\)
=\(\left(\dfrac{11}{7}+\dfrac{8}{35}\right):\left(\dfrac{-39}{20}\right)\)
=\(\dfrac{9}{5}:\left(\dfrac{-39}{20}\right)\)
=\(\dfrac{9.\left(-20\right)}{5.39}\)
=\(\dfrac{3.\left(-4\right)}{1.13}\)
=\(\dfrac{-12}{13}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
=(-5/28+7/4+8/35):(-69)/20
=(-25/140+245/140+32/140)x(-20)/69
=252/140x(-20)/69
=-12/23
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\dfrac{4}{5}\); \(\dfrac{3}{4}\); \(\dfrac{11}{13}\)
b) \(\dfrac{25}{35}\); \(\dfrac{100}{140}\); \(\dfrac{85}{119}\)
a) Những phân số tối giản là: \(\dfrac{4}{5};\dfrac{3}{4};\dfrac{11}{13}\)
b) Những phân số bằng \(\dfrac{5}{7}\) là: \(\dfrac{25}{35};\dfrac{100}{140};\dfrac{16}{28};\dfrac{85}{119}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a, 1/2 x ( 2/9 + 3/7 - 5/27 )
= 1/2 x ( 41/63 - 5/27 )
= 1/2 x 88/189
= 44/189
b, (-5/8 + 1,75 + 8/35) : (-3 và 9/10)
= (-5/8 + 7/4 + 8/35) : (-39/10)
= (9/8 + 8/35) : (-39/10)
=379/280 : (-39/10)
= -379/1092
c, 1/3 x 5/7 - 5/27 x 36/14
= 5/21 - 10/21
= -5/21
Chúc bạn học tốt !
a) 1/2 x (\(\frac{42}{189}-\frac{81}{189}-\frac{35}{189}\))=1/2 x 88/189 = 44/189
b) ( \(\frac{-5}{8}+\frac{7}{4}+\frac{8}{35}\)) : \(-3\frac{9}{10}\)
= ( \(\frac{-175}{280}+\frac{490}{280}+\frac{64}{280}\)) : \(\frac{-39}{10}\)
=\(\frac{379}{280}\) x \(\frac{-10}{39}\)=\(\frac{-379}{1092}\)
c) \(\frac{5}{21}\)- \(\frac{10}{21}\)= \(\frac{-5}{21}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có : ( -5/28 + 7/4 + 8/35 ) : ( -69/20 ) .
= ( -25/140 + 245/140 + 32/140 ) * ( -20/69 ) .
= 9/5 * ( -20/69 ) .
= -12/23 .
![](https://rs.olm.vn/images/avt/0.png?1311)
- \(\dfrac{5}{11}\) = \(\dfrac{20}{x}\) = \(\dfrac{-35}{y}\)
\(x\) = 20 : (-\(\dfrac{5}{11}\))
\(x\) = -44
y = - 35 : (- \(\dfrac{5}{11}\))
y = 77
![](https://rs.olm.vn/images/avt/0.png?1311)
(\(-\frac{5}{28}+1,75+\frac{8}{35}\)) : (\(-3\frac{9}{20}\))
= \(\frac{9}{5}\) : \(-\frac{39}{10}\)
= \(-\frac{6}{13}\)
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