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24 tháng 5 2016

\(\frac{A}{5}=\frac{4}{35.31}+\frac{6}{35.41}+\frac{9}{50.41}+\frac{7}{50.57}=\frac{35-31}{35.31}+\frac{41-35}{35.41}+\frac{50-41}{50.41}+\frac{57-50}{50.57}\)

\(\frac{A}{5}=\frac{1}{31}-\frac{1}{35}+\frac{1}{35}-\frac{1}{41}+\frac{1}{41}-\frac{1}{50}+\frac{1}{50}-\frac{1}{57}=\frac{1}{31}-\frac{1}{57}\)=> A = 5. \(\left(\frac{1}{31}-\frac{1}{57}\right)\)

\(\frac{B}{2}=\frac{7}{38.31}+\frac{5}{38.43}+\frac{3}{43.46}+\frac{11}{46.57}=\frac{38-31}{31.38}+\frac{43-38}{38.43}+\frac{46-43}{43.46}+\frac{57-46}{46.57}\)

\(\frac{B}{2}=\frac{1}{31}-\frac{1}{38}+\frac{1}{38}-\frac{1}{43}+\frac{1}{43}-\frac{1}{46}+\frac{1}{46}-\frac{1}{57}=\frac{1}{31}-\frac{1}{57}\)=> B = 2.\(\left(\frac{1}{31}-\frac{1}{57}\right)\)

A/B = 5/2

11 tháng 3 2023

A= 

7.31

4

 + 

7.41

6

 + 

10.41

9

 + 

10.57

7

 ⇒ 

5

A

 = 

35.31

4

 + 

35.41

6

 + 

50.41

9

 + 

50.57

7

 

 

\dfrac{A}{5}=\dfrac{1}{31}-\dfrac{1}{35}+\dfrac{1}{35}-\dfrac{1}{41}+\dfrac{1}{41}-\dfrac{1}{50}+\dfrac{1}{50}-\dfrac{1}{57} 

5

A

 = 

31

1

 − 

35

1

 + 

35

1

 − 

41

1

 + 

41

1

 − 

50

1

 + 

50

1

 − 

57

1

 

 

\dfrac{A}{5}=\dfrac{1}{31}-\dfrac{1}{57}=\dfrac{26}{31.57}\Rightarrow A=\dfrac{130}{31.57} 

5

A

 = 

31

1

 − 

57

1

 = 

31.57

26

 ⇒A= 

31.57

130

 

11 tháng 3 2023

T viết nhầm

11 tháng 8 2017

A = \(\frac{4}{7}.31+\frac{6}{7}.41+\frac{9}{10}.41+\frac{7}{10}.57\)

\(\left[\left(\frac{4}{7}+\frac{6}{7}\right).\left(31+41\right)\right]+\left[\left(\frac{9}{10}+\frac{7}{10}\right).\left(41+57\right)\right]\)

\(\frac{10}{7}.72+\frac{8}{5}.98\)

\(\left(\frac{10}{7}+\frac{8}{5}\right).\left(72+98\right)\)

\(\left(\frac{50}{35}+\frac{56}{35}\right).170\)

\(\frac{106}{35}.170\)

\(\frac{3604}{7}\)

B = \(\frac{7}{19}.31+\frac{5}{19}.43+\frac{3}{23}.43+\frac{11}{23}.57\)

\(\left[\left(\frac{7}{19}+\frac{5}{19}\right).\left(31+43\right)\right]+\left[\left(\frac{3}{23}+\frac{11}{23}\right).\left(43+57\right)\right]\)

\(\frac{12}{19}.74+\frac{14}{23}.100\)

\(\left(\frac{12}{19}+\frac{14}{23}\right).\left(100+74\right)\)

\(\left(\frac{276}{437}+\frac{266}{437}\right).174\)

\(\frac{542}{437}.174\)

\(\frac{79674}{437}\)

A : B = \(\frac{3604}{7}:\frac{19674}{437}=\frac{3604.437}{7.19674}=\frac{1802.2.437}{7.9837.2.}=\frac{1802.437}{7.9837}\)

16 tháng 8 2015

Có thể : đề ở câu A sửa 51 thành 57

\(\frac{A}{5}=\frac{4}{35.31}+\frac{6}{35.41}+\frac{9}{50.41}+\frac{7}{50.57}=\frac{35-31}{35.31}+\frac{41-35}{35.41}+\frac{50-41}{50.41}+\frac{57-50}{50.57}\)

\(\frac{A}{5}=\frac{1}{31}-\frac{1}{35}+\frac{1}{35}-\frac{1}{41}+\frac{1}{41}-\frac{1}{50}+\frac{1}{50}-\frac{1}{57}=\frac{1}{31}-\frac{1}{57}\)=> A = 5. \(\left(\frac{1}{31}-\frac{1}{57}\right)\)

\(\frac{B}{2}=\frac{7}{38.31}+\frac{5}{38.43}+\frac{3}{43.46}+\frac{11}{46.57}=\frac{38-31}{31.38}+\frac{43-38}{38.43}+\frac{46-43}{43.46}+\frac{57-46}{46.57}\)

\(\frac{B}{2}=\frac{1}{31}-\frac{1}{38}+\frac{1}{38}-\frac{1}{43}+\frac{1}{43}-\frac{1}{46}+\frac{1}{46}-\frac{1}{57}=\frac{1}{31}-\frac{1}{57}\)=> B = 2.\(\left(\frac{1}{31}-\frac{1}{57}\right)\)

A/B = 5/2

25 tháng 2 2019

\(A=\dfrac{4}{7.31}+\dfrac{6}{7.41}+\dfrac{9}{10.41}+\dfrac{7}{10.57}\)

\(=\dfrac{20}{35.31}+\dfrac{30}{35.41}+\dfrac{45}{50.41}+\dfrac{35}{50.57}\)

\(=5\left(\dfrac{4}{35.31}+\dfrac{6}{35.41}+\dfrac{9}{50.41}+\dfrac{7}{50.57}\right)\)

\(=5\left(\frac{1}{31}-\dfrac{1}{35}+\dfrac{1}{35}-\dfrac{1}{41}+\dfrac{1}{41}-\dfrac{1}{50}+\dfrac{1}{50}-\dfrac{1}{57}\right)\)

\(=5\left(\dfrac{1}{31}-\dfrac{1}{57}\right)\)

\(B=\dfrac{7}{19.31}+\dfrac{5}{19.43}+\dfrac{3}{23.43}+\dfrac{11}{23.57}\)

\(=\dfrac{14}{34.31}+\dfrac{10}{38.43}+\dfrac{6}{46.43}+\dfrac{22}{46.57}\)

\(=2\left(\dfrac{7}{34.31}+\dfrac{5}{38.43}+\dfrac{3}{46.43}+\dfrac{11}{46.57}\right)\)

\(=2\left(\dfrac{1}{31}-\dfrac{1}{34}+\dfrac{1}{34}-\dfrac{1}{43}+\dfrac{1}{43}-\dfrac{1}{46}+\dfrac{1}{46}-\dfrac{1}{57}\right)\)

\(=2\left(\dfrac{1}{31}-\dfrac{1}{57}\right)\)

\(\Rightarrow\dfrac{A}{B}=\frac{5\left(\dfrac{1}{31}-\dfrac{1}{57}\right)}{2\left(\dfrac{1}{31}-\dfrac{1}{57}\right)}=\dfrac{5}{2}\)

14 tháng 5 2019

A=47.31+67.41+910.41+710.57A=47.31+67.41+910.41+710.57

=2035.31+3035.41+4550.41+3550.57=2035.31+3035.41+4550.41+3550.57

=5(435.31+635.41+950.41+750.57)=5(435.31+635.41+950.41+750.57)

=5(131−135+135−141+141−150+150−157)=5(131−135+135−141+141−150+150−157)

=5(131−157)=5(131−157)

B=719.31+519.43+323.43+1123.57B=719.31+519.43+323.43+1123.57

=1434.31+1038.43+646.43+2246.57=1434.31+1038.43+646.43+2246.57

=2(734.31+538.43+346.43+1146.57)=2(734.31+538.43+346.43+1146.57)

=2(131−134+134−143+143−146+146−157)=2(131−134+134−143+143−146+146−157)

=2(131−157)=2(131−157)

⇒AB=5131−1572131−157=52

18 tháng 5 2022

\(A=\dfrac{4}{7.31}+\dfrac{6}{7.41}+\dfrac{9}{10.41}+\dfrac{7}{10.57}\Rightarrow\dfrac{A}{5}=\dfrac{4}{35.31}+\dfrac{6}{35.41}+\dfrac{9}{50.41}+\dfrac{7}{50.57}\)

\(\dfrac{A}{5}=\dfrac{1}{31}-\dfrac{1}{35}+\dfrac{1}{35}-\dfrac{1}{41}+\dfrac{1}{41}-\dfrac{1}{50}+\dfrac{1}{50}-\dfrac{1}{57}\)

\(\dfrac{A}{5}=\dfrac{1}{31}-\dfrac{1}{57}=\dfrac{26}{31.57}\Rightarrow A=\dfrac{130}{31.57}\)

\(\dfrac{B}{2}=\dfrac{7}{38.31}+\dfrac{5}{38.41}+\dfrac{3}{46.43}+\dfrac{11}{46.57}\Rightarrow\dfrac{B}{2}=\dfrac{1}{31}-\dfrac{1}{57}=\dfrac{26}{31.57}\)

\(\Rightarrow B=\dfrac{52}{31.57}\)

\(\dfrac{A}{B}=\dfrac{130}{31.51}:\dfrac{52}{31.57}=\dfrac{5}{2}\)

18 tháng 5 2022

Ta có : `A:5=4/35.31+6/35.41++9/50.41+7/50.57`

`A/5 = 1/31 - 1/35 +1/35-1/41+1/41-1/50+1/50-1/57`

`A/5 =1/31-1/57` `(1)`

Lại có : `B:2=7/38.31 +5/38.43+3/46.43+11/46.57`

`B/2 =1/31-1/38+1/38-1/43+1/43-1/46+1/46-1/57`

`B/2 =1/31-1/57` `(2)`

Từ `(1)` và `(2)` `=>A/5 =B/2`

                         `=>A/B=5/2`