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12 tháng 4

=12+13+25+57+16−435+141

=(12+13+16)+(25+57−435)+141

=(36+26+16)+(1435+2535−435)+141

=3+2+16+14+25−435+141

=1+1+141

=2+141

=2141=8341
 

17 tháng 8 2023

a, \(\dfrac{1}{2}\) - ( - \(\dfrac{1}{3}\) ) + \(\dfrac{1}{23}\) + \(\dfrac{1}{6}\)

 =  \(\dfrac{5}{6}\)  + \(\dfrac{1}{23}\) + \(\dfrac{1}{6}\)

= 1 + \(\dfrac{1}{23}\)

 = \(\dfrac{24}{23}\) 

b, \(\dfrac{11}{24}\) - \(\dfrac{5}{41}\) + \(\dfrac{13}{24}\) + 0,5 - \(\dfrac{36}{41}\)

= (\(\dfrac{11}{24}\) + \(\dfrac{13}{24}\)) - ( \(\dfrac{5}{41}\) + \(\dfrac{36}{41}\)) + 0,5

= 1 - 1 + 0,5

= 0,5 

 

17 tháng 8 2023

c,\(-\dfrac{1}{12}-\left(\dfrac{1}{6}-\dfrac{1}{4}\right)\)

=\(-\dfrac{1}{12}-\left(-\dfrac{1}{12}\right)\)

=0

d, \(\dfrac{1}{6}-\left[\dfrac{1}{6}-\left(\dfrac{1}{4}+\dfrac{9}{12}\right)\right]\)

\(\dfrac{1}{6}-\left[\dfrac{1}{6}-1\right]\)

\(\dfrac{1}{6}-\left(-\dfrac{5}{6}\right)\)

= 1

15 tháng 4 2017

\(0,5+\dfrac{1}{3}+0,4+\dfrac{5}{7}+\dfrac{1}{6}-\dfrac{4}{35}+\dfrac{1}{41}\)

\(=\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{2}{5}+\dfrac{5}{7}+\dfrac{1}{6}-\dfrac{4}{35}+\dfrac{1}{41}\)

\(=\left(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{6}\right)+\left(\dfrac{2}{5}+\dfrac{5}{7}-\dfrac{4}{35}\right)+\dfrac{1}{41}\)

\(=\left(\dfrac{3}{6}+\dfrac{2}{6}+\dfrac{1}{6}\right)+\left(\dfrac{14}{35}+\dfrac{25}{35}-\dfrac{4}{35}\right)+\dfrac{1}{41}\)

\(=\dfrac{3+2+1}{6}+\dfrac{14+25-4}{35}+\dfrac{1}{41}\)

\(=1+1+\dfrac{1}{41}\)

\(=2+\dfrac{1}{41}\)

\(=2\dfrac{1}{41}=\dfrac{83}{41}\)

a) Ta có: \(D=\dfrac{1}{3}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{24}+\dfrac{1}{48}+\dfrac{1}{96}\)

\(=\dfrac{2}{3}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{12}+\dfrac{1}{12}-\dfrac{1}{24}+\dfrac{1}{24}-\dfrac{1}{48}+\dfrac{1}{48}-\dfrac{1}{96}\)

\(=\dfrac{2}{3}-\dfrac{1}{96}\)

\(=\dfrac{63}{96}=\dfrac{21}{32}\)

b)

Sửa đề: \(E=\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+...+\dfrac{1}{2048}\)

Ta có: \(E=\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+...+\dfrac{1}{2048}\)

\(\Leftrightarrow\dfrac{1}{2}\cdot E=\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+\dfrac{1}{32}+...+\dfrac{1}{4096}\)

\(\Leftrightarrow\dfrac{1}{2}\cdot E=\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{16}+...+\dfrac{1}{2048}-\dfrac{1}{4096}\)

\(\Leftrightarrow\dfrac{E}{2}=\dfrac{1}{2}-\dfrac{1}{4096}=\dfrac{2047}{4096}\)
hay \(E=\dfrac{2047}{2048}\)

30 tháng 6 2016
  1. C = \(\frac{83}{41}\)
  2. D = \(\frac{-79}{90}\)
20 tháng 4 2016

C=0.5+1/3+0.4+5/7+1/6-4/35+1/41

C=1/2+1/3+2/5+5/7+1/6-4/35+1/41

C=(1/2+1/6+1/3)+(2/5+5/7-4/35)+1/41

C=1+1-1/41

C=2-1/41

=>C=81/41

D=1/90-1/72-1/56-1/42-1/30-1/20--1/12-1/6-1/2

=> D=1/9*10-1/8*9-1/7*8-1/6*7-1/5*6-1/4*5-1/3*4-1/2*3-1/1*2

=>D=-(1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10)
=>D=-(1-1/10)

=>D=-9/10

ai k mh mh k lại

5 tháng 3 2018

C.D=18/10 nha

3 tháng 4 2019

Ta có 

C=\(\frac{1}{2}+\frac{1}{3}+\frac{2}{5}+\frac{5}{7}+\frac{1}{6}-\frac{4}{35}+\frac{1}{41}\)

\(\left(=\right)C=\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{6}\right)+\left(\frac{2}{5}+\frac{5}{7}-\frac{4}{35}\right)+\frac{1}{41}\)

\(\left(=\right)C=\left(\frac{3}{6}+\frac{2}{6}+\frac{1}{6}\right)+\left(\frac{14}{35}+\frac{25}{35}-\frac{4}{35}\right)+\frac{1}{41}\)

\(\left(=\right)c=1+\left(-1\right)+\frac{1}{41}=\frac{1}{41}\)

vì viết dưới dạng phân số chưa quen nên bn thông cảm cho mk nhé!

C = 0,5 + 1/3 + 0,4 + 5/7 + 1/6 - 4/35 + 1/41

= 5/10 + 1/3 + 4/10 + 5/7 + 1/6 - 4/35 + 1/41

= 1/2 + 1/3 + 2/5 + 5/7 + 1/6 - 4/35 + 1/41

= (1/2 + 1/3 + 1/6) + (2/5 + 5/7 - 4/35) +1/41

= (3/6+ 2/6 + 1/6) + ( 14/35 + 25/35 - 4/35) + 1/41

= 6/6 + 35/35 + 1/41

= 1 + 1 + 1/41 = 2 + 1/41 = 2/1 + 1/41

= 43/41 + 1/41 = 44/41

chúc bn học tốt

Giải:

A=1/10+1/40+1/88+1/154+1/238+1/340

A=1/2.5+1/5.8+1/8.11+1/11.14+1/14.17+1/17.20

A=1/2-1/5+1/5-1/8+1/8-1/11+1/11-1/14+1/14-1/17+1/17-1/20

A=1/2-1/20

A=9/20

D=1/3+1/6+1/12+1/24+1/48

D=1/3+1/2.3+1/3.4+1/4.6+1/6.8

D=1/3+1/2-1/3+1/3-1/4+1/2.(2/4.6+2/6.8)

D=1/3+1/2-1/4+1/2.(1/4-1/6+1/6-1/8)

D=1/3+1/4+1/2.(1/4-1/8)

D=1/3+1/4+1/2.1/8

D=1/3+1/4+1/16

D=31/48

F=0,5-1/3-0,4-4/7-1/6+4/35-1/41

F=1/2-1/3-2/5-4/7-1/6+4/35-1/41

F=1/6-(-6/35)-1/6+4/35-1/41

F=(1/6-1/6)+(6/35+4/35)-1/41

F=0+2/7-1/41

F=2/7+1/41

F=75/287

Chúc bạn học tốt!

24 tháng 4 2021

Cảm ơn nhìu <3

4 tháng 5 2018

1 .

[ 6 + ( 1/2 ) 3 - /-0,5/ ] : 3/12

= [ 6 + 1/8 - ( -5/10 ) ] . 12/3

= [ 6 + 1/8 + 5/10 ] .4

= [ 6 + 1/8 + 1/2 ] .4

= [ 48/8 + 1/8 + 4/8 ] .4

= 53/8 . 4

= 53 . 1/2

= 53/2

2.

1/3 + 5/4 : (-35/16)

= 1/3 + 5/4 . ( 16/-35 )

= 1/3 + 1 . 4/4 . (-7 )

= 1/3 + 4/28

= 1/3 + 1/7

= 7/21 + 3/21

= 10/21

3 .

11 3/13 - ( 2 4/7 + 5 3/13 )

= 11 3/13 - 2 4/7 - 5 3/13

= { [ ( 11 - 5 ) . ( 3/13 - 3/13 ) } - 2 4/7

= ( 6 . 0 ) - 2 4/7

= 0 - 18/7

= 18/7

4 .

1 3/7 + (-1/3 + 2 4/7 )

= 1 3/7 + ( -1 )/3 + 2 4/7

={ [ ( 1 + 2 ) . ( 3/7 + 4/7 ) } + ( -1 )/3

= ( 3 . 1 ) + ( -1 )/3

= 3 + ( -1 )/3

= 9/3 + ( -1 )/3

= 8/3

5 .

( 6 4/9 + 3 7/11 ) - 4 4/9

= 6 4/9 + 3 7/11 - 4 4/9

= { ( 6 - 4 ) . ( 4/9 - 4/9 ) } + 3 7/11

= ( 2 . 0 ) + 3 7/11

= 0 + 40/11

= 40/11

Nếu đúng thì k cho mình nha !