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![](https://rs.olm.vn/images/avt/0.png?1311)
![](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
![](https://rs.olm.vn/images/avt/0.png?1311)
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, \(\frac{11}{120}=\frac{11.40}{120.40}=\frac{440}{4800}\)
\(\frac{7}{40}=\frac{7.120}{40.120}=\frac{840}{4800}\)
b,\(\frac{24}{146}=\frac{24.13}{146.13}=\frac{312}{1898}\)
\(\frac{6}{13}=\frac{6.146}{13.146}=\frac{876}{1898}\)
c,\(\frac{7}{30}=\frac{7.60.40}{30.60.40}=\frac{16800}{72000}\)
\(\frac{13}{60}=\frac{13.30.40}{60.30.40}=\frac{15600}{72000}\)
\(\frac{-9}{40}=\frac{-9.60.30}{40.60.30}=\frac{-16200}{72000}\)
d,\(\frac{17}{60}=\frac{17.18.90}{60.18.90}=\frac{27540}{97200}\)
\(\frac{-5}{18}=\frac{-5.60.90}{18.60.90}=\frac{-27000}{97200}\)
\(\frac{-64}{90}=\frac{-64.18.60}{90.18.60}=\frac{-69120}{97200}\)
740 =7.12040.120 =8404800
b,24146 =24.13146.13 =3121898
1360 =13.30.4060.30.40 =1560072000
−940 =−9.60.3040.60.30 =−1620072000
d,1760 =17.18.9060.18.90 =2754097200
−518 =−5.60.9018.60.90 =−2700097200
−6490 =−64.18.6090.18.60 =−6912097200
Đúng 0 Sai 1613 =6.14613.146 =8761898
c,
![](https://rs.olm.vn/images/avt/0.png?1311)
a: 3/8=36/96
5/12=40/96
b: -2/9=-24/108
-5/12=-45/108
c: -3/16=-63/336
-5/24=-70/336
-21/56=-126/336
![](https://rs.olm.vn/images/avt/0.png?1311)
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
\(\dfrac{17}{60}=\dfrac{17\cdot3}{60\cdot3}=\dfrac{51}{180}\)
\(\dfrac{-5}{18}=\dfrac{\left(-5\cdot10\right)}{18\cdot10}=\dfrac{-50}{180}\)
\(\dfrac{-64}{90}=\dfrac{\left(-64\cdot2\right)}{90\cdot2}=\dfrac{-128}{180}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
ta có : \(\frac{17}{60};\frac{-5}{18};\frac{-64}{90}=\frac{-32}{45}\) ( MC : 180 )
quy đồng : \(\frac{17}{60}=\frac{17.3}{60.3}=\frac{51}{180};\frac{-5}{18}=\frac{-5.10}{18.10}=\frac{-50}{180};\frac{-32}{45}=\frac{-32.4}{45.4}=\frac{-128}{180}\)
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