7/19

7/4

7/5

a7/19

b7/4

c7/5

7/19

7/4

21/15

Hướng dẫn: Chia cả tử và mẫu cho UCLN của chúng:

ƯCLN(-25 ,-75) = 25. Do đó:

\(\dfrac{121\times75\times130\times169}{39\times60\times11\times198}\)

\(=\dfrac{25\times169}{6\times18}\)

\(=\dfrac{4225}{108}\)

668068830000

= 199377750/5096520

=4225/108

\(\dfrac{24}{32}=\dfrac{24:8}{32:8}=\dfrac{3}{4}\)

\(\dfrac{75}{100}=\dfrac{75:25}{100:25}=\dfrac{3}{4}\)

\(\dfrac{45}{60}=\dfrac{45:15}{60:15}=\dfrac{3}{4}\)

\(\dfrac{27}{63}=\dfrac{27:9}{63:9}=\dfrac{3}{7}\)

\(\dfrac{24}{32}=\dfrac{24:8}{32:8}=\dfrac{3}{4}\)

\(\dfrac{45}{6}=\dfrac{45:3}{6:3}=\dfrac{15}{2}\)

\(\dfrac{75}{100}=\dfrac{75:25}{100:25}=\dfrac{3}{4}\)

\(\dfrac{27}{63}=\dfrac{27:9}{63:9}=\dfrac{3}{7}\)

1) \(\dfrac{5}{10}=\dfrac{5:5}{10:5}=\dfrac{1}{2}\)

\(\dfrac{-18}{-27}=\dfrac{-18:\left(-9\right)}{-27:\left(-9\right)}=\dfrac{2}{3}\)

\(\dfrac{-42}{105}=\dfrac{-42:21}{105:21}=\dfrac{-2}{5}\)

\(\dfrac{75}{-135}=\dfrac{75:\left(-15\right)}{-135:\left(-15\right)}=\dfrac{-5}{9}\)

\(\dfrac5{10}=\dfrac{5.1}{5.2}=\dfrac12\\\dfrac{-18}{-27}=\dfrac{(-9).2}{(-9).3}=\dfrac23\\\dfrac{-42}{105}=\dfrac{21.(-2)}{21.5}=\dfrac{-2}5\\\dfrac{75}{-135}=\dfrac{(-15).(-5)}{(-15).9}=\dfrac{-5}9\)

`5/10=1/2`

`-18/-27=2/3`

-42/105=-2/5`

`75/-135=-5/9``

 Ta có: \(\frac{{12}}{{ - 24}} = \frac{{12:12}}{{ - 24:12}} = \frac{1}{{ - 2}}\)

\(\frac{{ - 39}}{{75}} = \frac{{ - 39:3}}{{75:3}} = \frac{{ - 13}}{{25}}\)

\(\frac{{132}}{{ - 264}} = \frac{{132:132}}{{ - 264:132}} = \frac{1}{{ - 2}}\).