MC(BCNN)=120

Ta có:\(\frac{7}{40}=\frac{7.3}{40.3}=\frac{21}{120}\)

và giữ nguyên \(\frac{11}{120}\)

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, \(\frac{7}{40}=\frac{7x3}{40x3}=\frac{21}{120}\) và \(\frac{11}{120}\)

b, \(\frac{24}{146}=\frac{12}{73}=\frac{12x13}{73x13}=\frac{156}{949}\)

\(\frac{6}{13}=\frac{6x73}{13x73}=\frac{438}{949}\)

sao bạn k làm đc

dễ

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)\(\frac{1}{11}\)và -6

-6 = \(\frac{-6}{1}\) =\(\frac{-66}{11}\)

b)\(\frac{13}{120}\) và \(\frac{7}{40}\)

\(\frac{7}{40}\) = \(\frac{21}{120}\)

mk chỉ lm đc đến đây thôi!!!

còn lại tự lm nha!

chúc cậu học tốt!!!!!!!!!!!!!!!!!!