K
Khách

Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.

29 tháng 10 2021

a: \(x\cdot\dfrac{3}{4}+x=\dfrac{7}{8}\)

\(\Leftrightarrow x\cdot\dfrac{7}{4}=\dfrac{7}{8}\)

\(\Leftrightarrow x=\dfrac{1}{2}\)

D
datcoder
CTVVIP
21 tháng 9 2023

a) \(\dfrac{2}{3}+\dfrac{3}{4}< x< 1\dfrac{1}{3}+\dfrac{4}{5}\)

\(\dfrac{2\times4}{3\times4}+\dfrac{3\times3}{4\times3}< x< \dfrac{\left(1\times3+1\right)\times5}{3\times5}+\dfrac{4\times3}{5\times3}\)

\(\dfrac{8}{12}+\dfrac{9}{12}< x< \dfrac{20}{15}+\dfrac{12}{15}\\ \dfrac{17}{12}< x< \dfrac{32}{15}\)

Ước tính: \(\dfrac{17}{12}=1,4\) và \(\dfrac{32}{15}=2,1\). Vậy số tự nhiên x = 2 sẽ thõa mãn 1,4 < x < 2,1

b)

 \(\dfrac{5}{6}-\dfrac{1}{4}< x< 2\dfrac{1}{3}-\dfrac{2}{5}\\ \dfrac{5\times4}{6\times4}-\dfrac{1\times6}{4\times6}< x< \dfrac{\left(2\times3+1\right)\times5}{3\times5}-\dfrac{2\times3}{5\times3}\\ \dfrac{20}{24}-\dfrac{6}{24}< x< \dfrac{35}{15}-\dfrac{6}{15}\\ \dfrac{14}{24}< x< \dfrac{29}{15}\)

Ước tính \(\dfrac{14}{24}=0,5\) và \(\dfrac{29}{15}=1,9\)

Vậy với x là số tự nhiên x = 1 sẽ thõa mãn 0,5 < x < 1,9

21 tháng 9 2023

1,4 là sao mik chưa học ,

3 tháng 8 2023

\(a,2\dfrac{2}{5}:y\times1\dfrac{3}{4}=\dfrac{7}{8}\\ \dfrac{12}{5}:y\times\dfrac{7}{4}=\dfrac{7}{8}\\ \dfrac{12}{5}:y=\dfrac{7}{8}:\dfrac{7}{4}\\ \dfrac{12}{5}:y=\dfrac{1}{2}\\ y=\dfrac{12}{5}:\dfrac{1}{2}=\dfrac{24}{5}\\ b,3\dfrac{2}{5}:y:1\dfrac{1}{4}=2\dfrac{3}{5}\\ \dfrac{17}{5}:y:\dfrac{5}{4}=\dfrac{13}{5}\\ y:\dfrac{5}{4}=\dfrac{17}{5}:\dfrac{13}{5}\\ y:\dfrac{5}{4}=\dfrac{17}{13}\\ y=\dfrac{17}{13}\times\dfrac{5}{4}=\dfrac{85}{52}\)

3 tháng 8 2023

\(c,\dfrac{12}{5}-2\dfrac{2}{5}\times y=1\dfrac{1}{4}\\ \dfrac{12}{5}-\dfrac{12}{5}\times y=\dfrac{5}{4}\\ \dfrac{12}{5}\times y=\dfrac{12}{5}-\dfrac{5}{4}\\ \dfrac{12}{5}\times y=\dfrac{23}{20}\\ y=\dfrac{23}{20}:\dfrac{12}{5}\\ y=\dfrac{23}{48}\)

28 tháng 3 2022

ai giúp mik ik T_T

5 tháng 8 2023

a, \(\dfrac{7}{8}\) \(\times\) \(\dfrac{3}{13}\) + \(\dfrac{4}{9}\) \(\times\) \(\dfrac{4}{13}\)

\(\dfrac{1}{13}\) \(\times\)\(\dfrac{21}{8}\) + \(\dfrac{16}{9}\))

\(\dfrac{1}{13}\) \(\times\)\(\dfrac{189}{72}\) + \(\dfrac{128}{72}\))

\(\dfrac{1}{13}\) \(\times\)  \(\dfrac{317}{73}\)

\(\dfrac{317}{949}\)

b, \(\dfrac{6}{5}\) + \(\dfrac{7}{3}\) + \(\dfrac{8}{9}\)

=   \(\dfrac{54}{45}\) + \(\dfrac{105}{45}\) + \(\dfrac{40}{45}\)

\(\dfrac{199}{45}\)

c, 23 : \(\dfrac{5}{14}\) + \(\dfrac{6}{7}\) + \(\dfrac{4}{9}\)

=   \(\dfrac{322}{5}\) + \(\dfrac{6}{7}\) + \(\dfrac{4}{9}\)

\(\dfrac{20286}{315}\) + \(\dfrac{270}{315}\) + \(\dfrac{140}{315}\)

\(\dfrac{20696}{315}\)

d, 4\(\dfrac{1}{4}\) + 7\(\dfrac{3}{7}\) - 2\(\dfrac{4}{17}\)

= 4 + \(\dfrac{1}{4}\) + 7 + \(\dfrac{3}{7}\) - 2 - \(\dfrac{4}{17}\)

= (4+7-2) + (\(\dfrac{1}{4}\) + \(\dfrac{3}{7}\) - \(\dfrac{4}{17}\))

= 9 + \(\dfrac{119}{476}\) + \(\dfrac{204}{476}\) - \(\dfrac{112}{476}\)

= 9\(\dfrac{211}{476}\) = \(\dfrac{4495}{476}\)

e, 8 - (9\(\dfrac{2}{11}\) + \(\dfrac{8}{33}\))

= 8 - 9 - \(\dfrac{2}{11}\) - \(\dfrac{8}{33}\)

=  -1 - \(\dfrac{2}{11}\)  - \(\dfrac{8}{33}\)

\(\dfrac{-33}{33}\) - \(\dfrac{-6}{33}\) -  \(\dfrac{8}{33}\)

= - \(\dfrac{47}{33}\)

4 tháng 5 2022

\(\dfrac{1}{3}+\dfrac{2}{3}=\dfrac{3}{3}=1\)

\(\dfrac{4}{5}+\dfrac{5}{6}=\dfrac{24}{30}+\dfrac{25}{30}=\dfrac{49}{30}\)

\(\dfrac{4}{5}-\dfrac{3}{5}=\dfrac{1}{5}\)

\(\dfrac{8}{5}x\dfrac{5}{8}=\dfrac{1}{1}=1\)

\(\dfrac{6}{7}x\dfrac{4}{7}=\dfrac{24}{49}\)

\(\dfrac{4}{5}:\dfrac{4}{5}=\dfrac{4}{5}x\dfrac{5}{4}=\dfrac{1}{1}=1\)

\(\dfrac{5}{5}:\dfrac{5}{5}=\dfrac{5}{5}x\dfrac{5}{5}=\dfrac{1}{1}=1\)

4 tháng 5 2022

1) \(\dfrac{1}{3}+\dfrac{2}{3}=\dfrac{1+2}{3}=\dfrac{3}{3}=1\)

2) \(\dfrac{4}{5}+\dfrac{5}{6}=\dfrac{24}{30}+\dfrac{25}{30}=\dfrac{24+25}{30}=\dfrac{49}{30}\)

3) \(\dfrac{4}{5}-\dfrac{3}{5}=\dfrac{4-3}{5}=\dfrac{1}{5}\)

4) \(\dfrac{9}{8}-\dfrac{4}{2}=\dfrac{9}{8}-2=\dfrac{9}{8}-\dfrac{16}{8}=-\dfrac{7}{8}\)

5) \(\dfrac{8}{5}\times\dfrac{5}{8}=\dfrac{8\times5}{5\times8}=\dfrac{40}{40}=1\)

6) \(\dfrac{6}{7}\times\dfrac{4}{7}=\dfrac{6\times4}{7}=\dfrac{24}{7}\)

7) \(\dfrac{4}{5}:\dfrac{4}{5}=\dfrac{4}{5}\times\dfrac{5}{4}=\dfrac{4\times5}{5\times4}=\dfrac{20}{20}=1\)

8) \(\dfrac{5}{5}:\dfrac{5}{5}=\dfrac{5}{5}\times\dfrac{5}{5}=\dfrac{5\times5}{5\times5}=\dfrac{25}{25}=1\)

5 tháng 6 2023

\(3\dfrac{1}{2}+4\dfrac{5}{7}-5\dfrac{5}{14}\)

\(\dfrac{7}{2}+\dfrac{33}{7}-\dfrac{75}{14}\)

\(\dfrac{49}{14}+\dfrac{66}{14}-\dfrac{75}{14}\)

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

\(4\dfrac{1}{2}+\dfrac{1}{2}\div5\dfrac{1}{2}\)

=\(\dfrac{9}{2}+\dfrac{1}{2}\div\dfrac{11}{2}\)

=\(\dfrac{9}{2}+\dfrac{1}{2}\times\dfrac{2}{11}\)

=\(\dfrac{9}{2}+\dfrac{1}{11}\)

=\(\dfrac{101}{22}\)

\(x\times3\dfrac{1}{3}=3\dfrac{1}{3}\div4\dfrac{1}{4}\)

\(x\times\dfrac{10}{3}=\dfrac{10}{3}\div\dfrac{17}{4}\)

\(x\times\dfrac{10}{3}=\dfrac{10}{3}\times\dfrac{4}{17}\)

\(x\times\dfrac{10}{3}=\dfrac{40}{51}\)

\(x=\dfrac{40}{51}\div\dfrac{10}{3}\)

\(x=\dfrac{40}{51}\times\dfrac{3}{10}\)

\(x=\dfrac{120}{510}=\dfrac{12}{51}=\dfrac{4}{7}\)

\(5\dfrac{2}{3}\div x=3\dfrac{2}{3}-2\dfrac{1}{2}\)

\(\dfrac{17}{3}\div x=\dfrac{11}{3}-\dfrac{5}{2}\)

\(\dfrac{17}{3}\div x=\dfrac{7}{6}\)

\(x=\dfrac{17}{3}\div\dfrac{7}{6}\)

\(x=\dfrac{17}{3}\times\dfrac{6}{7}\)

\(x=\dfrac{102}{21}=\dfrac{34}{7}\)

a) ....

=> 14/3 : x = 4/3 + 3/5 = 29/15

=> x = 14/3 : 29/15 = 70/29

b) ...

=> 4/3 + 5/2x = 2

=> 5/2x = 2 - 4/3 = 2/3

=> x = 2/3 : 5/2 = 4/15

c)...

=> x : 10/3 =  31/10

=> x = 31/10 x 10/3 = 31/3 

19 tháng 2 2023

`3/4 + 5/6 = 9/12 + 10/12 = 19/12`

`1/2 + 7/12 = 6/12 + 7/12 = 13/12`

`2/3 xx 3/4 = 2/4 = 1/2`

`7/4 : 2 = 7/4 xx 1/2 = 7/8`

19 tháng 2 2023

\(a,\dfrac{3}{4}+\dfrac{5}{6}=\dfrac{18}{24}+\dfrac{20}{24}=\dfrac{38}{24}=\dfrac{19}{12}\)

\(b,\dfrac{1}{2}+\dfrac{7}{12}=\dfrac{6}{12}+\dfrac{7}{12}=\dfrac{13}{12}\)

\(c,\dfrac{2}{3}x\dfrac{3}{4}=\dfrac{2}{4}\)

\(d,\dfrac{7}{4}:2=\dfrac{7}{4}x\dfrac{1}{2}=\dfrac{7}{8}\)

1 tháng 7 2021

\(a,5x\dfrac{7}{3}=\dfrac{5}{1}x\dfrac{7}{3}=\dfrac{35}{3};b,\dfrac{13}{4}:7=\dfrac{13}{4} :\dfrac{7}{1}=\dfrac{13}{4}x\dfrac{1}{7}=\dfrac{13}{28}\)

1 tháng 7 2021

1. Tính 

\(a,5\times\dfrac{7}{3}=\dfrac{35}{3}\)

\(b,\dfrac{13}{4}:7=\dfrac{13}{4}\times\dfrac{1}{7}=\dfrac{13}{28}\)

2. Tính

\(a,\dfrac{3}{7}+\dfrac{2}{5}+\dfrac{3}{4}\)

\(=\dfrac{15}{35}+\dfrac{14}{35}+\dfrac{3}{4}\)

\(=\dfrac{29}{35}+\dfrac{3}{4}\)

\(=\dfrac{116}{140}+\dfrac{105}{140}\)

\(=\dfrac{221}{140}\)

\(b,\dfrac{9}{7}-\dfrac{5}{11}\times\dfrac{11}{7}\)

\(=\dfrac{9}{7}-\dfrac{55}{77}\)

\(=\dfrac{99}{77}-\dfrac{55}{77}\)

\(=\dfrac{44}{77}=\dfrac{4}{7}\)

\(c,\dfrac{3}{5}\times\dfrac{5}{7}+\dfrac{4}{7}\)

\(=\dfrac{3}{5}\times\left(\dfrac{5}{7}+\dfrac{4}{7}\right)\)

\(=\dfrac{3}{5}\times\dfrac{9}{7}\)

\(=\dfrac{27}{35}\)

\(d,\dfrac{7}{9}\times\dfrac{2}{5}:\dfrac{3}{11}\)

\(=\dfrac{14}{45}:\dfrac{3}{11}\)

\(=\dfrac{14}{45}\times\dfrac{11}{3}\)

\(=\dfrac{154}{135}\)

\(e,\dfrac{9}{7}+\dfrac{2}{3}-\dfrac{1}{4}\)

\(=\dfrac{27}{21}+\dfrac{14}{21}-\dfrac{1}{4}\)

\(=\dfrac{41}{21}-\dfrac{1}{4}\)

\(=\dfrac{164}{84}-\dfrac{21}{84}\)

\(=\dfrac{143}{84}\)

\(g,\dfrac{4}{9}:\dfrac{3}{5}\times\dfrac{2}{11}\)

\(=\dfrac{4}{9}\times\dfrac{5}{3}\times\dfrac{2}{11}\)

\(=\dfrac{20}{27}\times\dfrac{2}{11}\)

\(=\dfrac{40}{297}\)

\(h,\dfrac{7}{2}-\dfrac{3}{10}:\dfrac{2}{5}\)

\(=\left(\dfrac{7}{2}-\dfrac{3}{10}\right):\dfrac{2}{5}\)

\(=\left(\dfrac{35}{10}-\dfrac{3}{10}\right):\dfrac{2}{5}\)

\(=\dfrac{32}{10}:\dfrac{2}{5}\)

\(=\dfrac{16}{5}\times\dfrac{5}{2}\)

\(=\dfrac{80}{10}=8\)

16 tháng 10 2023

`3/5 : x =1/3 +1/2`

` 3/5 : x= 2/6 +3/6`

` 3/5 : x= 5/6`

` x= 3/5 : 5/6`

` x= 3/5 xx 6/5`

` x= 18/25`

__

`x: 7/15 =2`

` x= 2xx 7/15`

` x= 14/15`

__

`x-3/2=11/4-5/4`

`x-3/2= 6/4`

`x= 3/2 +3/2`

`x= 6/2`

`x=3`

__

`x+5/4 = 3/2+7/12`

`x+5/4 = 18/12+7/12`

`x+5/4 = 25/12`

`x= 25/12-5/4`

`x= 25/12- 15/12`

`x= 10/12`

`x= 5/6`