c 212121/353535

=212121:21/353535:35

=10101/10101

=212121:10101/353535:10101

=21/35

a. \(-\frac{15}{90}=-\frac{1}{6};\frac{120}{600}=\frac{1}{5};-\frac{75}{150}=-\frac{1}{2}\)

Mẫu chung: 30

\(-\frac{1}{6}=-\frac{5}{30};\frac{1}{5}=\frac{6}{30};-\frac{1}{2}=-\frac{15}{30}\)

b. \(\frac{54}{-90}=\frac{3}{-5}=-\frac{3}{5};-\frac{180}{288}=-\frac{5}{8};\frac{60}{-135}=\frac{4}{-9}=-\frac{4}{9}\)

Mẫu chung: 360

\(-\frac{3}{5}=-\frac{216}{360};-\frac{5}{8}=-\frac{225}{360};-\frac{4}{9}=-\frac{160}{360}\).

ko biet gi ca

anh ko biet

f, \(\dfrac{165}{270}\) = \(\dfrac{165:15}{270:15}\) = \(\dfrac{11}{18}\) = \(\dfrac{11\times6}{18\times6}\) = \(\dfrac{66}{108}\)

 \(\dfrac{91}{156}\) = \(\dfrac{91:13}{156:13}\) = \(\dfrac{7}{12}\) = \(\dfrac{7\times9}{12\times9}\) = \(\dfrac{63}{108}\)

\(\dfrac{210}{1134}\) = \(\dfrac{210:42}{1134:42}\) = \(\dfrac{5}{27}\) =  \(\dfrac{5\times4}{27\times4}\) = \(\dfrac{20}{108}\)

g, \(\dfrac{21}{9}\) = \(\dfrac{21:3}{9:3}\) = \(\dfrac{7}{3}\) = \(\dfrac{7\times10}{3\times10}\) = \(\dfrac{70}{30}\)

     \(\dfrac{120}{50}\) =  \(\dfrac{120:10}{50:10}\) = \(\dfrac{12}{5}\) = \(\dfrac{12\times6}{5\times6}\) = \(\dfrac{72}{30}\)

       \(\dfrac{63}{54}\) = \(\dfrac{63:9}{54:9}\) = \(\dfrac{7}{6}\)  = \(\dfrac{7\times5}{6\times5}\) = \(\dfrac{35}{30}\)

h, \(\dfrac{75}{100}\) = \(\dfrac{75:25}{100:4}\) = \(\dfrac{3}{4}\) = \(\dfrac{3\times9}{4\times6}\) = \(\dfrac{27}{36}\)

      \(\dfrac{150}{90}\) = \(\dfrac{150:30}{90:30}\) =  \(\dfrac{5}{3}\) = \(\dfrac{5\times12}{3\times12}\) = \(\dfrac{60}{36}\)

       \(\dfrac{250}{900}\) = \(\dfrac{250:50}{900:50}\) = \(\dfrac{5}{18}\)  = \(\dfrac{5\times2}{18\times2}\) = \(\dfrac{10}{36}\)

a) -15/90=-5/30=1/6

120/600=12/60=4/20=1/5

-75/150=-15/30=-5/10=-1/2

b)54/-90=6/-10=3/-5

-180/288=-90/144=-10/16=-5/8

60/-135=20/-45=4/-9

a: 27/-180=-27/180=-3/20=-21/140

-6/-35=6/35=24/120

-3/-28=3/28=15/140

b: \(\dfrac{3\cdot4+3\cdot7}{6\cdot5+9}=\dfrac{3\left(4+7\right)}{30+9}=\dfrac{11}{13}=\dfrac{2849}{13\cdot259}\)

\(\dfrac{6\cdot9-2\cdot17}{63\cdot6-119}=\dfrac{54-34}{259}=\dfrac{20}{259}=\dfrac{260}{259\cdot13}\)

a. \(\dfrac{1}{5}\) đã tối giản

\(\dfrac{4}{120}=\dfrac{1}{30}\)

\(\dfrac{-50}{60}=\dfrac{-5}{6}\)

Quy đồng: \(BCNN\left(5,30,6\right)=30\)

\(\Rightarrow\dfrac{1}{5}=\dfrac{1.6}{5.6}=\dfrac{6}{30};\dfrac{1}{30}=\dfrac{1.1}{30.1}=\dfrac{1}{30};\dfrac{-5}{6}=\dfrac{-5.5}{6.5}=\dfrac{-25}{30}\)

b. \(\dfrac{-25}{30}< \dfrac{1}{30}< \dfrac{6}{30}\)

a,\(\dfrac{4}{120}=\dfrac{1}{30};\dfrac{-50}{60}=\dfrac{-5}{6}\)  

\(\dfrac{1}{5}=\dfrac{1.6}{5.6}=\dfrac{6}{30};\dfrac{1}{30};\dfrac{-5}{6}=\dfrac{-5.5}{6.5}=\dfrac{-25}{30}\)

b, Vì \(\dfrac{6}{30}>\dfrac{1}{30}>\dfrac{-25}{30}\) nên => \(\dfrac{4}{120}>\dfrac{1}{30}>\dfrac{-50}{60}\)

a) \(\dfrac{2}{36}=\dfrac{1}{18}\)

\(\dfrac{8}{12}=\dfrac{2}{3}\)

b) \(\dfrac{10}{25}=\dfrac{2}{5}\)

\(\dfrac{14}{40}=\dfrac{7}{20}\)