\(\dfrac{-5}{6}=\dfrac{-5\times4}{6\times4}=\dfrac{-20}{24}\)

\(\dfrac{3}{-8}=\dfrac{3\times\left(-3\right)}{-8\times\left(-3\right)}=\dfrac{-9}{24}\)

\(2=\dfrac{48}{24}\)

\(\dfrac{-25}{100}=\dfrac{-1}{4}=\dfrac{-1\times6}{4\times6}=\dfrac{-6}{24}\)

\(\dfrac{72}{108}=\dfrac{2}{3}=\dfrac{2\times8}{3\times8}=\dfrac{16}{24}\)

\(a,-\dfrac{10}{21}=\dfrac{-2}{7}.\dfrac{5}{3}=\dfrac{-2}{3}.\dfrac{5}{7}\\ b,\dfrac{2}{21}=\dfrac{1}{3}.\dfrac{2}{7}=\dfrac{1}{7}.\dfrac{2}{3}\\ c,\dfrac{8}{15}=\dfrac{2}{3}.\dfrac{4}{5}=\dfrac{4}{3}.\dfrac{2}{5}\)

Câu 1:

MSC=60

7/10=7.6/10.6=42/60            5/-12=-5/12=-5.5/12.5=-25/60

Câu 2:

17/34=1/2;  -12/22=-6/11;  -25/35=-5/7;  125/75=5/3

Câu 3:

MSC=24

1/3=1.8/3.8=8/24     -3/8=-3.3/8.3=-9/24           17/24=17/24

a)

 \(3:8=\dfrac{3}{8}\)

\(8:9=\dfrac{8}{9}\)

\(4:7=\dfrac{4}{7}\)

\(12:5=\dfrac{12}{5}\)

b)

 \(7=\dfrac{7}{1}\)

\(9=\dfrac{9}{1}\)

\(21=\dfrac{21}{1}\)

\(40=\dfrac{40}{1}\)

1.
a) 10=\(\dfrac{40}{4}\)

b) 25= \(\dfrac{100}{4}\)

2.

a) 11=\(\dfrac{11}{1}\)

b) 276=\(\dfrac{276}{1}\)

c) 158=\(\dfrac{158}{1}\)

3.

\(\dfrac{1}{1};\dfrac{2}{2};\dfrac{3}{3};\dfrac{4}{4};\dfrac{5}{5}\)

− 5 6 = − 10 24 ; 3 − 8 = − 9 24 ; 7 12 = 14 24 ; − 25 100 = − 1 4 = − 6 24 72 108 = 2 3 = 16 24 ; 10 60 = 1 6 = 4 24

− 5 6 = − 10 24 ; 3 − 8 = − 9 24 ; 7 12 = 14 24 ; − 25 100 = − 1 4 = − 6 24 72 108 = 2 3 = 16 24 ; 10 60 = 1 6 = 4 24

a, \(\frac{-3}{1}\), \(\frac{4}{1}\),\(\frac{12}{1}\)

b,\(\frac{12}{3}\). \(\frac{-15}{3}\), \(\frac{33}{3}\)

c, \(\frac{21}{-3}\),\(\frac{48}{-3}\), \(\frac{-66}{-3}\)