\(a.\\ 5:\left(-13\right)=\dfrac{-5}{13}\)

\(b.\\ x:3=\dfrac{x}{3}\)

\(c.\\ 6=\dfrac{6}{1}\)

\(d.\\ 1.25=\dfrac{5}{4}\)

5:(-13)

Bài 5:

\(\dfrac{3}{4}=\dfrac{x}{20}=\dfrac{21}{y}\)

=>\(\left\{{}\begin{matrix}\dfrac{x}{20}=\dfrac{3}{4}\\\dfrac{21}{y}=\dfrac{3}{4}\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}x=20\cdot\dfrac{3}{4}=15\\y=21\cdot\dfrac{4}{3}=7\cdot4=28\end{matrix}\right.\)

Bài 4:

a: \(\dfrac{3}{5}=\dfrac{3\cdot9}{5\cdot9}=\dfrac{27}{45}\)

b: Đề sai rồi bạn

Bài 3:

a: \(21\cdot21=441\)

\(49\cdot9=441\)

=>\(21\cdot21=49\cdot9\)

=>\(\dfrac{21}{9}=\dfrac{49}{21}\)

b: \(\dfrac{-24}{34}=\dfrac{-24:2}{34:2}=\dfrac{-12}{17}\)

\(\dfrac{-60}{85}=\dfrac{-60:5}{85:5}=\dfrac{-12}{17}\)

Do đó: \(\dfrac{-24}{34}=\dfrac{-60}{85}\)

Bài 2:

\(15cm=\dfrac{3}{20}m\)

\(40mm=\left(\dfrac{40}{1000}\right)m=\dfrac{1}{25}m\)

Bài 1:

a: \(\left(-17\right):8=\dfrac{-17}{8}\)

b: \(\left(-8\right):\left(-9\right)=\dfrac{-8}{-9}\)

a: \(0.\left(13\right)=\dfrac{13}{99}\)

b: \(0,\left(4\right)+1,\left(4\right)=\dfrac{4}{9}+\dfrac{13}{9}=\dfrac{17}{9}\)

a. \(\dfrac{13}{99}\)

b.\(\dfrac{17}{9}\)

A=13/100

a. 3 : 11 = \(\dfrac{3}{11}\)

b. -4 : 7 = \(\dfrac{-4}{7}\)

c 5 : ( -13)  = \(\dfrac{5}{-13}=\dfrac{-5}{13}\)

d x : 3 \(\left(x\in z\right)\)

= \(\dfrac{x}{3}\)

\(a,3:11=\dfrac{3}{11}=\dfrac{-3}{-11}\\ b,-4:7=\dfrac{-4}{7}=\dfrac{4}{-7}\\ c,5:\left(-13\right)=\dfrac{5}{-13}=\dfrac{-5}{13}\\ d,x:3=\dfrac{x}{3}=\dfrac{-x}{-3}\)

a ) 9 13 b ) 11 − 5 c ) − 4 11 . d ) − 2 − 13 .

a)  9 13

b)  11 - 5

c)  - 4 11

d)  - 2 - 13

\(\dfrac{435}{113}\)viết dưới dạng phép chia có dư là: đc 3 dư 96

các phân số lớn hơn 1 là : \(\dfrac{9}{8};\dfrac{19}{17};\dfrac{27}{24}\)

các phân số nhỏ hơn 1 là

\(\dfrac{13}{17};\dfrac{5}{6}\)

\(a,\dfrac{-3}{4}\\ \\b,\dfrac{1}{20}\\ c,\dfrac{-3}{-7}\)