
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.


1a. chọn mẫu chung là 120,ta có
\(\frac{7}{30}=\frac{7.4}{30.4}=\frac{28}{120}\)
\(\frac{13}{60}=\frac{13.2}{60.2}=\frac{26}{120}\)
\(\frac{-9}{40}=\frac{-9.3}{40.3}=\frac{27}{120}\)
vậy....
1b. chon mẫu số chung là 60
\(\frac{3}{-20}=\frac{-3.3}{20.3}=-\frac{9}{60}\)
\(\frac{-11}{-30}=\frac{-11.\left(-2\right)}{-30.\left(-2\right)}=\frac{22}{60}\)
\(\frac{7}{15}=\frac{7.4}{15.4}=\frac{28}{60}\)
2a.\(\frac{-15}{90}=\frac{-1}{6};\frac{120}{600}=\frac{1}{5};\frac{-75}{150}=\frac{-1}{2}\)
mẫu chung 30
\(\frac{-1}{6}=-\frac{5}{30};\frac{1}{5}=\frac{16}{30};-\frac{1}{2}=\frac{-15}{30}\)
vậy...

a: \(\dfrac{-7}{15}=\dfrac{-7\cdot4}{15\cdot4}=\dfrac{-28}{60}\)
\(\dfrac{5}{12}=\dfrac{5\cdot5}{12\cdot5}=\dfrac{25}{60}\)
b: \(\dfrac{1}{5}=\dfrac{1\cdot6}{5\cdot6}=\dfrac{6}{30}\)
\(\dfrac{-2}{3}=\dfrac{-2\cdot10}{3\cdot10}=\dfrac{-20}{30}\)
\(\dfrac{7}{10}=\dfrac{7\cdot3}{10\cdot3}=\dfrac{21}{30}\)
c: \(\dfrac{-15}{50}=\dfrac{-15\cdot3}{50\cdot3}=\dfrac{-45}{150}\)
\(\dfrac{9}{10}=\dfrac{9\cdot15}{10\cdot15}=\dfrac{135}{150}\)
\(\dfrac{26}{-30}=\dfrac{-26}{30}=\dfrac{-26\cdot5}{30\cdot5}=\dfrac{-130}{150}\)
d: \(\dfrac{7}{10}=\dfrac{7\cdot51}{10\cdot51}=\dfrac{357}{510}\)
\(\dfrac{-5}{-15}=\dfrac{1}{3}=\dfrac{1\cdot170}{3\cdot170}=\dfrac{170}{510}\)
\(\dfrac{3}{17}=\dfrac{3\cdot30}{17\cdot30}=\dfrac{90}{510}\)
e: \(\dfrac{-4}{-75}=\dfrac{4}{75}=\dfrac{4}{75}\)
\(\dfrac{-3}{5}=\dfrac{-3\cdot15}{5\cdot15}=\dfrac{-45}{75}\)
\(\dfrac{8}{25}=\dfrac{8\cdot3}{25\cdot3}=\dfrac{24}{75}\)
f: \(-\dfrac{4}{5}=\dfrac{-4\cdot7}{5\cdot7}=\dfrac{-28}{35}\)
\(\dfrac{6}{7}=\dfrac{6\cdot5}{7\cdot5}=\dfrac{30}{35}\)

a: \(\dfrac{5}{7}=\dfrac{5\cdot11}{7\cdot11}=\dfrac{55}{77}\)
\(\dfrac{9}{11}=\dfrac{9\cdot7}{11\cdot7}=\dfrac{63}{77}\)
b: \(\dfrac{36}{42}=\dfrac{6}{7}=\dfrac{6\cdot9}{7\cdot9}=\dfrac{54}{63}\)
\(-\dfrac{12}{54}=\dfrac{-2}{9}=\dfrac{-2\cdot7}{9\cdot7}=-\dfrac{14}{63}\)
c: \(\dfrac{-11}{30}=\dfrac{-11\cdot4}{30\cdot4}=\dfrac{-44}{120}\)
\(\dfrac{-17}{-40}=\dfrac{17}{40}=\dfrac{17\cdot3}{40\cdot3}=\dfrac{51}{120}\)
d: \(\dfrac{36}{42}=\dfrac{6}{7}=\dfrac{6\cdot3}{7\cdot3}=\dfrac{18}{21}\)
\(\dfrac{-12}{36}=\dfrac{-1}{3}=\dfrac{-1\cdot7}{3\cdot7}=\dfrac{-7}{21}\)

1. \(\frac{9}{30}=\frac{3}{10};\frac{98}{80}=\frac{49}{40};\frac{15}{1000}=\frac{3}{200}\)
Vì \(200⋮10;200⋮40\)
=> BCNN(10; 40; 200) = 200
200 : 10 = 20
200 : 40 = 5
=> \(\frac{3}{10}=\frac{3\cdot20}{10\cdot20}=\frac{60}{200}\), \(\frac{49}{40}=\frac{49\cdot5}{40\cdot5}=\frac{245}{200}\)

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
613 =6.14613.146 =8761898
c,


\(a,\frac{3}{20}=\frac{3\times3}{20\times3}=\frac{9}{60}\)
\(\frac{7}{30}=\frac{7\times2}{30\times2}=\frac{14}{60}\)
\(\frac{4}{15}=\frac{4\times4}{15\times4}=\frac{16}{60}\)
\(c,\frac{7}{-30}=\frac{7\times4}{\left(-30\right)\times4}=\frac{28}{-120}\)
\(\frac{3}{-40}=\frac{3\times3}{\left(-40\right)\times3}=\frac{9}{-120}\)
\(-\frac{11}{30}=\frac{\left(-11\right)\times4}{30\times4}=-\frac{44}{120}\)