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ta có : \(\frac{17}{60};\frac{-5}{18};\frac{-64}{90}=\frac{-32}{45}\) ( MC : 180 )
quy đồng : \(\frac{17}{60}=\frac{17.3}{60.3}=\frac{51}{180};\frac{-5}{18}=\frac{-5.10}{18.10}=\frac{-50}{180};\frac{-32}{45}=\frac{-32.4}{45.4}=\frac{-128}{180}\)
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a) 7/30;13/60;-9/40(MSC=120)
=>7/30= 28/120;13/60=26/120; -9/40=-27/120.
b)17/60;-5/18;-64/90(MSC=180)
=> 17/60=51/180;-5/18=-50/180;-64/90=-128/180.
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có
13 = 13
60 = 22 . 3 . 5
40 = 23. 5
BCNN ( 13, 60, 40 ) = 23. 3 .5 . 13 = 1560
MC : 1560
Thừa số phụ
1560 : 13 =120
1560 : 60 = 26
1560 : 40 = 39
Ta co
7/13 = 7.120/13.120=840/1560
13/60 = 13 . 26/ 60.26 = 338/1560
-9/40 = - 9 . 39/ 40 . 39 = -351/ 1560
Ta có -64 / 90 = -32/45
60 = 22 . 3. 5
18 = 2 . 32
45 = 32. 5
BCNN ( 60, 18, 45 ) = 22 . 32 . 5 = 180
MC : 180
Thừa số phụ
180 : 60 = 3
180 : 18 = 10
180 : 45 = 4
Ta có
17/60 = 17 . 3/ 60. 3 = 51/180
-5/18 = -5 . 10/18.10 = -50/180
-64/90 = -32/45 = -32 . 4 / 45 . 4 = -128/180
Mong các bạn nha
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a) \(-\dfrac{5}{14}=-\dfrac{5.3}{14.3}=-\dfrac{15}{42}\)
\(\dfrac{1}{-21}=-\dfrac{1}{21}=-\dfrac{1.2}{21.2}=-\dfrac{2}{42}\)
b) \(\dfrac{17}{60}=\dfrac{17.3}{60.3}=\dfrac{51}{180}\)
\(\dfrac{-5}{18}=\dfrac{-5.10}{18.10}=-\dfrac{50}{180}\)
\(-\dfrac{64}{90}=-\dfrac{64.2}{90.2}=-\dfrac{128}{180}\)
a)-5/14 và 1/-21
-5/14=-5.-21/14.-2=105/-28
![](https://rs.olm.vn/images/avt/0.png?1311)
a: 17/60=51/180
-5/18=-50/180
-64/90=-128/180
b: -6/-35=6/35=48/280
3/28=30/280
27/-180=-3/20=-42/280
17 x 3/ 60 x 3 = 51/180
-5 x10/18 x 10 = -50/180
-64 x2/90 x2 = -128/180
\(\dfrac{17}{60};\dfrac{-5}{18};\dfrac{-64}{90}\) MSC : 180
\(\dfrac{17}{60}=\dfrac{17\cdot3}{60\cdot3}=\dfrac{51}{180}\)
\(\dfrac{-5}{18}=\dfrac{\left(-5\cdot10\right)}{18\cdot10}=\dfrac{-50}{180}\)
\(\dfrac{-64}{90}=\dfrac{\left(-64\cdot2\right)}{90\cdot2}=\dfrac{-128}{180}\)