K
Khách

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

4 tháng 4 2020

a, 2/3+1/2+1/6

=4/6+3/6+1/6

=4/3

b, 5/12+5/6-3/4

=10/24+20/24-18/24

=1/2

c, 1/3*3/5*2/5

=(1*3*2)/(3*5*5)

=2/25

d, 15/16:3/8*3/4

= 15/16*8/3*3/4

= 15/8

4 tháng 4 2020

a) \(\frac{2}{3}\)+\(\frac{1}{2}\)+\(\frac{1}{6}\)  = \(\frac{4}{6}\)+\(\frac{3}{6}\)+\(\frac{1}{6}\)     =\(\frac{8}{6}\)  =\(\frac{4}{3}\)

b)\(\frac{5}{12}+\frac{5}{6}-\frac{3}{4}\)=\(\frac{5}{12}+\frac{10}{12}-\frac{9}{12}\)=\(\frac{6}{12}\)\(\frac{1}{2}\)

c) \(\frac{1}{3}\cdot\frac{3}{5}\cdot\frac{2}{5}\)        =\(\frac{6}{75}\)=\(\frac{2}{25}\)

\(a,\frac{2}{3}+\frac{1}{2}+\frac{1}{6}=\frac{4}{6}+\frac{3}{6}+\frac{1}{6}=\frac{8}{6}=\frac{4}{3}\)

\(b,\frac{5}{12}+\frac{5}{6}-\frac{3}{4}=\frac{5}{12}+\frac{10}{12}-\frac{9}{12}=\frac{6}{12}=\frac{1}{2}\)

a) 2/3 + 1/2 + 1/6 =  4/6 + 3/6 +  1/6 = 7/6 + 1/6 = 8/6 = 4/3 

 b) 5/12 + 5/6 - 3/4 = 5/12 + 10/12 - 9/12 = 15/12 - 9/12 = 6/12 = 1/2

 c) 1/3 x 3/5 x 2/5 = 3/15 x 2/5 = 6/75  = 2/25

 d) 15/16 : 3/8 x 3/4 = 15/16 x 8/3 x 3/4 = 1/10 x 3/4 = 3/40 

2 tháng 7 2019

Bài 1:

2 tháng 7 2019

Bài 1: 1/3+1/9+1/27+1/81+1/243+1/729

Đặt:
A = 1 + 1/3 + 1/9 + 1/27 + 1/81 + 1/243 + 1/729
Nhân A với 3 ta có:
\(Ax3=3+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}\)
\(\Rightarrow Ax3-S=3-\frac{1}{243}\)
\(\Rightarrow2A=\frac{2186}{729}\)
\(\Rightarrow A=\frac{2186}{729}:2\)
\(\Rightarrow A=\frac{1093}{729}\)

24 tháng 9 2017

25-2 : (3/5-1/2) + (5/2 +1/5 * 1/4 )

= 25 - 2 : 1/10 + (5/2 + 1/20)

= 25 - 20 + 51/20

= 5 + 51/20

\(5\frac{51}{20}\)

( 3/10+ 4/5 *1/2 ) : (17/9 -4/3 : 3)

= (3/10 + 2/5) : (17/9 - 4/9)

= (-1/10) : 13/9

= -9/130

7 tháng 9 2019

Từng dòng là 1 bài nhé mọi nguoiwf jup Mk nhanh vs

30 tháng 6

a; 5\(\dfrac{3}{4}\) : 3 + 2\(\dfrac{1}{4}\).\(\dfrac{1}{3}\) - \(\dfrac{3}{8}\)

\(\dfrac{23}{4}\) : 3 + \(\dfrac{9}{4}\).\(\dfrac{1}{3}\) - \(\dfrac{3}{8}\)

\(\dfrac{23}{4}\) x \(\dfrac{1}{3}\) + \(\dfrac{3}{4}\) - \(\dfrac{3}{8}\)

\(\dfrac{23}{12}\) + \(\dfrac{3}{4}\) - \(\dfrac{3}{8}\)

\(\dfrac{46}{24}\) + \(\dfrac{18}{24}\) - \(\dfrac{9}{24}\)

\(\dfrac{64}{24}\) - \(\dfrac{9}{24}\)

\(\dfrac{55}{24}\)

21 tháng 9 2020

                                                            Bài giải

\(\frac{2}{3}+\frac{3}{4}+\frac{4}{5}=\frac{40}{60}+\frac{45}{60}+\frac{48}{60}=\frac{133}{60}\)

\(\frac{8}{5}+\frac{7}{6}+\frac{10}{9}+\frac{1}{2}=\frac{144}{90}+\frac{105}{90}+\frac{100}{90}+\frac{45}{90}=\frac{394}{90}\)

\(\frac{15}{17}-\frac{11}{13}+\frac{3}{26}=\frac{390}{442}+\frac{374}{442}+\frac{51}{442}=\frac{815}{442}\)

\(\frac{9}{12}\text{ x }\frac{4}{3}\text{ : }\frac{8}{5}=\frac{9}{12}\text{ x }\frac{4}{3}\text{ x }\frac{5}{8}=\frac{9\text{ x }4\text{ x }5}{12\text{ x }3\text{ x }8}=\frac{5}{8}\)

\(\frac{4}{5}\text{ x }\frac{15}{8}\text{ : }\frac{5}{7}=\frac{4}{5}\text{ x }\frac{15}{8}\text{ x }\frac{7}{5}=\frac{4\text{ x }15\text{ x }7}{5\text{ x }8\text{ x }5}=\frac{21}{10}\)

26 tháng 4 2021

\(\frac{2}{3}+\frac{3}{4}+\frac{4}{5}=\frac{40}{60}+\frac{45}{60}+\frac{48}{60}=\frac{133}{60}\) 

\(\frac{8}{5}+\frac{7}{6}+\frac{10}{9}+\frac{1}{2}=\frac{144}{90}+\frac{105}{90}+\frac{100}{90}+\frac{45}{90}=\frac{197}{45}\)

\(\frac{15}{17}-\frac{11}{13}+\frac{1}{26}=\frac{390}{442}+\frac{374}{442}+\frac{51}{442}=\frac{815}{442}\)

\(\frac{9}{12}\times\frac{4}{3}:\frac{8}{5}=1:\frac{8}{5}=\frac{5}{8}\)

\(\frac{4}{5}\times\frac{15}{8}:\frac{5}{7}=\frac{3}{2}:\frac{5}{7}=\frac{21}{10}\)

28 tháng 7 2023

a) \(2+\dfrac{3}{4}\)

\(=\dfrac{8}{4}+\dfrac{3}{4}\)

\(=\dfrac{8+3}{4}\)

\(=\dfrac{11}{4}\)

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

\(=\dfrac{4}{12}+\dfrac{18}{12}-\dfrac{21}{12}\)

\(=\dfrac{4+18-21}{12}\)

\(=\dfrac{1}{12}\)

c) \(\dfrac{1}{6}+\dfrac{3}{8}-\dfrac{1}{4}\)

\(=\dfrac{4}{24}+\dfrac{9}{24}-\dfrac{6}{24}\)

\(=\dfrac{4+9-6}{24}\)

\(=\dfrac{7}{24}\)

d) \(\dfrac{5}{12}+\dfrac{3}{8}\times\dfrac{4}{9}\)

\(=\dfrac{5}{12}+\dfrac{3\times4}{8\times9}\)

\(=\dfrac{5}{12}+\dfrac{1}{6}\)

\(=\dfrac{5}{12}+\dfrac{2}{12}\)

\(=\dfrac{7}{12}\)

e) \(\dfrac{4}{5}-\dfrac{1}{5}\times\dfrac{7}{2}\)

\(=\dfrac{4}{5}-\dfrac{1\times7}{5\times2}\)

\(=\dfrac{4}{5}-\dfrac{7}{10}\)

\(=\dfrac{8}{10}-\dfrac{7}{10}\)

\(=\dfrac{8-7}{10}\)

\(=\dfrac{1}{10}\)

f) \(\dfrac{16}{9}-\dfrac{4}{15}:\dfrac{2}{5}\)

\(=\dfrac{16}{9}-\dfrac{4}{15}\times\dfrac{5}{2}\)

\(=\dfrac{16}{9}-\dfrac{4\times5}{15\times2}\)

\(=\dfrac{16}{9}-\dfrac{2}{3}\)

\(=\dfrac{16}{9}-\dfrac{6}{9}\)

\(=\dfrac{16-6}{9}\)

\(=\dfrac{10}{9}\)

a: =8/4+3/4=11/4

b: =4/12+18/12-21/12=1/12

c: =4/24+9/24-6/24=7/24

d: =5/12+12/72

=5/12+1/6

=5/12+2/12=7/12

e: =4/5-7/10

=8/10-7/10=1/10

f: =16/9-4/15*5/2

=16/9-20/30

=16/9-2/3

=16/9-6/9=10/9

11 tháng 9 2019

Bài 1 : \(\frac{2}{3}< \left[\frac{1}{6}+\frac{2}{15}+\frac{3}{40}+\frac{4}{96}\right]:5\times x< \frac{5}{6}\)

=> \(\frac{2}{3}< \left[\frac{1}{6}+\frac{2}{15}+\frac{3}{40}+\frac{1}{24}\right]:5\cdot x< \frac{5}{6}\)

=> \(\frac{2}{3}< \left[\frac{1}{6}+\frac{1}{24}+\frac{2}{15}+\frac{3}{40}\right]:5\cdot x< \frac{5}{6}\)

=> \(\frac{2}{3}< \frac{5}{12}:5\cdot x< \frac{5}{6}\)

=> \(\frac{2}{3}< \frac{1}{12}\cdot x< \frac{5}{6}\)

=> \(\frac{2}{3}< \frac{x}{12}< \frac{5}{6}\)

=> \(\frac{8}{12}< \frac{x}{12}< \frac{10}{12}\)

=> x = 9

Bài 2 : \(\frac{\left[\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\right]}{x}=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{132}\)

=> \(\frac{\left[1-\frac{1}{2}+\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{8}+\frac{1}{8}-\frac{1}{16}\right]}{x}=\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{11\cdot12}\)

=> \(\frac{\left[1-\frac{1}{16}\right]}{x}=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{11}-\frac{1}{12}\)

=> \(\frac{15}{\frac{16}{x}}=1-\frac{1}{12}\)

=> \(\frac{15}{\frac{16}{x}}=\frac{11}{12}\)

=> \(\frac{15}{16}:x=\frac{11}{12}\)

=> \(x=\frac{45}{44}\)

Bài 3 : \(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{1}{x\times(x+1):2}=\frac{399}{400}\)

=> \(\frac{2}{6}+\frac{2}{12}+\frac{2}{20}+...+\frac{2}{x\times(x+1)}=\frac{399}{400}\)

=> \(2\left[\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{x\times(x+1)}\right]=\frac{399}{400}\)

=> \(2\left[\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+...+\frac{1}{x\times(x+1)}\right]=\frac{399}{400}\)

=> \(\left[\frac{1}{2}-\frac{1}{3}+...+\frac{1}{x}-\frac{1}{x+1}\right]=\frac{399}{800}\)

=> \(\frac{1}{2}-\frac{1}{x+1}=\frac{399}{800}\)

=> \(\frac{1}{x+1}=\frac{1}{800}\)

=> x = 799

11 tháng 9 2019

Bài 2 :

\(\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\right):x=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{132}\) (*)

Ta có : \(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}=\frac{8}{16}+\frac{4}{16}+\frac{2}{16}+\frac{1}{16}=\frac{8+4+2+1}{16}=\frac{15}{16}\) (1)

Lại có : \(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{132}\)

\(=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{11.12}\)

\(=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{11}-\frac{1}{12}\)

\(=1\left(-\frac{1}{2}+\frac{1}{2}\right)+\left(-\frac{1}{3}+\frac{1}{3}\right)+...+\left(-\frac{1}{11}+\frac{1}{11}\right)-\frac{1}{12}\)

\(=1-\frac{1}{12}=\frac{11}{12}\) (2)

Thay (1) và (2) vào biểu thức (*) ta được :

\(\frac{15}{16}:x=\frac{11}{12}\)

\(\Leftrightarrow x=\frac{15}{16}:\frac{11}{12}\)

\(\Leftrightarrow x=\frac{45}{44}\)

Vậy : \(x=\frac{45}{44}\)