a) 1,5 : 2,16 

\(=\frac{15}{10}:\frac{216}{100}=\frac{3}{2}:\frac{54}{25}=\frac{3}{2}.\frac{25}{54}=\frac{25}{36}=25:36\)

Các câu còn lại lm tương tự

a) 1,2: 3,24 = 120 : 324 = 10:27

b) =

c) =

a)

b)

c)

d)

a) \(1,5:2,16=\frac{15}{10}:\frac{216}{100}=\frac{3}{2}:\frac{54}{25}=\frac{3}{2}.\frac{25}{54}=\frac{25}{36}=25:36\)

b) \(4\frac{2}{7}:\frac{3}{5}=\frac{30}{7}.\frac{5}{3}=\frac{50}{7}=50:7\)

c) \(\frac{2}{9}:0,31=\frac{2}{9}:\frac{31}{100}=\frac{2}{9}.\frac{100}{31}=\frac{200}{279}=200:279\)

a) \(1,2:3,36=\dfrac{6}{5}:\dfrac{84}{25}=\dfrac{5}{14}\)

b)\(3\dfrac{1}{7}:2\dfrac{5}{14}=\dfrac{22}{7}:\dfrac{33}{14}=\dfrac{4}{3}\)

c)\(\dfrac{3}{8}:0,54=\dfrac{3}{8}:\dfrac{27}{50}=\dfrac{25}{36}\)

a, 1,2 :3,36= \(\dfrac{6}{5}:\dfrac{84}{25}=\dfrac{5}{14}=5:14\)

\(3\dfrac{1}{7}:2\dfrac{5}{14}=\dfrac{22}{7}:\dfrac{33}{14}=\dfrac{4}{3}=4:3\)

\(\dfrac{3}{8}:0,54=\dfrac{3}{8}:\dfrac{27}{50}=\dfrac{25}{36}=25:36\)

a,\(\frac{30}{7}:\frac{3}{5}=\frac{30}{7}.\frac{5}{3}=\frac{50}{7}\)

b,\(\frac{2}{9}:\frac{31}{100}=\frac{2}{9}.\frac{100}{31}=\frac{200}{279}\)

Bài làm:

1)

Ta có:

a)  \(1,5\div2,16=\frac{25}{36}\)

b) \(4\div\frac{\frac{2}{7}}{\frac{3}{5}}=\frac{42}{5}\)

c) \(\frac{2}{9}\div0,31=\frac{200}{279}\)

2) Ta có: \(ad=bc\)

\(\Leftrightarrow\frac{ad}{cd}=\frac{bc}{cd}\)

\(\Rightarrow\frac{a}{c}=\frac{b}{d}\)

Bài 2:

ad = bc

Vì c, d khác 0 nên ta chai cả hai vế cho c.d khi đó ta được:

\(\frac{ad}{cd}\) = \(\frac{bc}{cd}\) = \(\frac{a}{c}=\frac{b}{d}\) (đpcm)

a, Ta có : \(1,2=\dfrac{12}{10}=\dfrac{6}{5}\) ; \(3,36=\dfrac{84}{25}\)

=> \(1,2:3,36=\dfrac{6}{5}:\dfrac{84}{25}=\dfrac{5}{14}\)

b, Ta có : \(3\dfrac{1}{7}:2\dfrac{5}{14}=\dfrac{22}{7}:\dfrac{33}{14}=\dfrac{4}{3}\)

c,\(\dfrac{3}{8}:0,54=\dfrac{3}{8}:\dfrac{27}{50}=\dfrac{25}{36}\)

Bài 1a:

\(\frac{4,6}{1,4}\) = \(\frac{11,5}{5x}\)

4,6 x 5\(x\) = 11,5 x 1,4

23\(x\) = 16,1

\(x\) = 16,1 : 23

\(x\) = 0,7

Vậy \(x\) = 0,7

Bài 1b:

\(\frac{x^2}{6}\) = \(\frac{24}{25}\)

25\(x^2\) = 24.6

25\(x^2\) = 144

\(x^2\) = 144/25

\(x\) = - 12/5 hoặc \(x\) = 12/5

Vậy \(x\) ∈ {-12/5; 12/5}

Bài 1c:

\(\frac{x+2}{2}\) = \(\frac{1}{1-x}\)

(\(x\) + 2)(1 - \(x\)) = 1.2

\(x\) - \(x^2\) + 2 - 2\(x\) = 2

\(x^2\) + (2\(x\) - \(x\)) + 2 - 2 = 0

\(x^2\) + \(x\) + 0 = 0

\(x\)(\(x\) + 1) = 0

\(x\) = 0

\(x\) + 1 = 0

\(x\) = - 1

Vậy \(x\) ∈ {-1; 0}