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21 tháng 5 2023

( 1/2 + 1/3 + 1/4 + ... + 1/10 ) . x = 1/9 + 2/8 + ... + 9/1

=> x = ( 1/9 + 2/8 + ... + 9/1 ) : ( 1/2 + 1/3 + ... 1/10 )

=> x = ( 9/1 + 8/2 + ... + 2/8 + 1/9 ) : ( 1/2 + 1/3 + 1/4 + ... + 1/10 )

=>x = [ ( 9 - 1 - 1 -... - 1 ) +( 8/2 + 1 ) + ( 7/3 + 1 ) + ... + ( 1/9 + 1 )  ] : ( 1/2 + 1/3 + 1/4 + ... + 1/10 )

=> x = (  1 + 10/2 + 10/3 + ... + 10/9 ) : ( 1/2 + 1/3 + 1/4 + ... + 1/10 )

=> x = [10 . ( 1/2 + 1/3 + ... + 1/9 ) ] : ( 1/2 + 1/3 + 1/4 + ... + 1/10 )

=> x = 10 

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#𝗝𝘂𝗻𝗻

17 tháng 6 2017

a)y=5/6

b)y=11/4

17 tháng 6 2017

\(a\left(\frac{1}{2}-\frac{1}{4}+....+\frac{1}{8}-\frac{1}{10}\right).y=\frac{1}{3}\)
\(\left(\frac{1}{2}-\frac{1}{10}\right).y=\frac{1}{3}\)

\(\frac{2}{5}.y=\frac{1}{3}\)

      \(y=\frac{1}{3}:\frac{2}{5}\)

     \(y=\frac{5}{6}\)

\(b,\left(\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+....+\frac{1}{9}-\frac{1}{11}\right).y=\frac{2}{3}\)

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

      \(\frac{10}{11}.y=\frac{2}{3}\)

              \(y=\frac{2}{3}:\frac{10}{11}\)

               \(y=\frac{22}{30}\)

7 tháng 9 2017

Mình chỉ biết kết quả là 1980 thôi . sorry!

22 tháng 10 2021

31886311680

25 tháng 6 2018

\(1,\\ x+\dfrac{1}{2}=-\dfrac{5}{3}\\ x=-\dfrac{5}{3}-\dfrac{1}{2}\\ x=-\dfrac{13}{6}\\ Vậyx=-\dfrac{13}{6}\)

\(2,\\ \dfrac{1}{3}-x=\dfrac{3}{5}\\ x=\dfrac{1}{3}-\dfrac{3}{5}\\ x=-\dfrac{4}{15}\\ Vậyx=-\dfrac{4}{15}\)

\(3,\\ 3-4+x=\dfrac{7}{2}\\ -1+x=\dfrac{7}{2}\\ x=\dfrac{7}{2}+1\\ x=\dfrac{9}{2}\\ Vậyx=\dfrac{9}{2}\)

\(4,\\ x-\dfrac{4}{3}=-\dfrac{7}{9}\\ x=-\dfrac{7}{9}+\dfrac{4}{3}\\ x=\dfrac{15}{27}\\ Vậyx=\dfrac{15}{27}\)

\(5,\\ x-\left(-\dfrac{7}{3}\right)=\dfrac{5}{6}\\ x=\dfrac{5}{6}-\dfrac{7}{3}\\ x=-\dfrac{27}{18}\\ Vậyx=-\dfrac{27}{18}\)

\(6,\\ x-\dfrac{1}{5}=\dfrac{9}{10}\\ x=\dfrac{9}{10}+\dfrac{1}{5}\\ x=\dfrac{11}{10}\\ Vậyx=\dfrac{11}{10}\)

\(7,\\ x+\dfrac{5}{12}=\dfrac{3}{8}\\ x=\dfrac{3}{8}-\dfrac{5}{12}\\ x=-\dfrac{1}{24}\\ Vậyx=-\dfrac{1}{24}\)

\(8,\\ x+\dfrac{5}{4}=\dfrac{7}{6}\\ x=\dfrac{7}{6}-\dfrac{5}{4}\\ x=-\dfrac{9}{24}\\ Vậyx=-\dfrac{9}{24}\)

\(9,\\ x-\dfrac{2}{7}=\dfrac{1}{35}\\ x=\dfrac{1}{35}+\dfrac{2}{7}\\ x=\dfrac{11}{35}\\ Vậyx=\dfrac{11}{35}\\ 10,\\ x-\dfrac{1}{5}=-\dfrac{7}{10}\\ x=-\dfrac{7}{10}+\dfrac{1}{5}\\ x=-\dfrac{1}{2}\\ Vậyx=-\dfrac{1}{2}\)

18 tháng 2 2021

ahiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii hãy ấn a

21 tháng 4 2017

a) \(\left(4\dfrac{1}{9}+3\dfrac{1}{4}\right).2\dfrac{1}{4}+2\dfrac{3}{4}\)

\(=\left(\dfrac{37}{9}+\dfrac{13}{4}\right).\dfrac{9}{4}+\dfrac{11}{4}\)

\(=\left(\dfrac{148}{36}+\dfrac{117}{36}\right).\dfrac{9}{4}+\dfrac{11}{4}\)

\(=\left(\dfrac{148+117}{36}\right).\dfrac{9}{4}+\dfrac{11}{4}\)

\(=\dfrac{265}{36}.\dfrac{9}{4}+\dfrac{11}{4}\)

\(=\dfrac{265.9}{36.4}+\dfrac{11}{4}\)

\(=\dfrac{265.1}{4.4}+\dfrac{11}{4}\)

\(=\dfrac{265}{16}+\dfrac{11}{4}\)

\(=\dfrac{265}{16}+\dfrac{44}{16}\)

\(=\dfrac{309}{16}\)

21 tháng 4 2017

thanks

29 tháng 7 2017

(1/2 + 1/3 + 1/4 +........+1/10 ) x X = 1/9 + 2/8 + .....+ 8/2 + 9/1

( 1/2 + 1/3 + 1/4 + ... + 1/10 ) x X = 1 + ( 1/9 + 1 ) + ( 2/8 + 1 ) + ... + ( 8/2 + 1 ) 

( 1/2 + 1/3 + 1/4 + ... + 1/10 ) x X = 10/10 + 10/9 + 10/8 + ... + 10/2 

( 1/2 + 1/3 + 1/4 + ... + 1/10 ) x X = 10 . ( 1/10 + 1/9 + 1/8 + ... + 1/2 )

X = \(\frac{10.\left(\frac{1}{10}+\frac{1}{9}+\frac{1}{8}+...+\frac{1}{2}\right)}{\frac{1}{2}+\frac{1}{3}+...+\frac{1}{9}+\frac{1}{10}}\)

X = 10

29 tháng 7 2017

 +Hình như B con thiếu 1/1 phải ko? 
B=1/1+1/2+1/3+1/4+...+1/9 
A=9/1+8/2+7/3+...+1/9=9+8/2+7/3+...+1/9 
=1+(1/9+1)+(2/8+1)+(3/7+1)+....+(8/2+1) 
=10/10+10/9+10/8+...+10/2=10(1/10+1/9+.... 
Vậy A=10B.Suy ra A:B=10 
+Nếu mà không thiếu thì dùng máy tính FX500MS,ES,phần mềm..v..v ta sẽ có 
A=4861/252 
B=4609/2520 
A/B=48610/4609

nếu B ko thiếu 1/1 thì mk chịu

27 tháng 6 2018

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

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

\(x=\dfrac{-10}{6}-\dfrac{3}{6}\)

Vậy \(x=\dfrac{-13}{6}\)

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

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

\(-x=\dfrac{9}{15}-\dfrac{5}{15}\)

\(-x=\dfrac{4}{15}\)

Vậy \(x=\dfrac{-4}{15}\)

3/ \(3-4+x=\dfrac{7}{2}\)

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

\(-4+x=\dfrac{7}{2}-\dfrac{6}{2}\)

\(-4+x=\dfrac{1}{2}\)

\(x=\dfrac{1}{2}+4\)

\(x=\dfrac{1}{2}+\dfrac{8}{2}\)

Vậy \(x=\dfrac{9}{2}\)

4/ \(x-\dfrac{4}{3}=\dfrac{-7}{9}\)

\(x=\dfrac{-7}{9}+\dfrac{4}{3}\)

\(x=\dfrac{-7}{9}+\dfrac{12}{9}\)

Vậy \(x=\dfrac{5}{9}\)

5/ \(x-\dfrac{-7}{2}=\dfrac{5}{6}\)

\(x=\dfrac{5}{6}-\dfrac{7}{2}\)

\(x=\dfrac{5}{6}-\dfrac{21}{6}\)

Vậy \(x=\dfrac{-16}{6}=\dfrac{-8}{3}\)

6/ \(x-\dfrac{1}{5}=\dfrac{9}{10}\)

\(x=\dfrac{9}{10}+\dfrac{1}{5}\)

\(x=\dfrac{9}{10}+\dfrac{2}{10}\)

Vậy \(x=\dfrac{11}{10}\)

7/ \(x+\dfrac{5}{12}=\dfrac{3}{8}\)

\(x=\dfrac{3}{8}-\dfrac{5}{12}\)

\(x=\dfrac{9}{24}-\dfrac{10}{24}\)

Vậy \(x=\dfrac{-1}{24}\)

8/ \(x+\dfrac{5}{4}=\dfrac{7}{6}\)

\(x=\dfrac{7}{6}-\dfrac{5}{4}\)

\(x=\dfrac{14}{12}-\dfrac{15}{12}\)

Vậy \(x=\dfrac{-1}{12}\)

9/ \(x-\dfrac{2}{7}=\dfrac{1}{35}\)

\(x=\dfrac{1}{35}+\dfrac{2}{7}\)

\(x=\dfrac{1}{35}+\dfrac{10}{35}\)

Vậy \(x=\dfrac{11}{35}\)

10 /\(x-\dfrac{1}{5}=\dfrac{-7}{10}\)

\(x=\dfrac{-7}{10}+\dfrac{1}{5}\)

\(x=\dfrac{-7}{10}+\dfrac{2}{10}\)

Vậy \(x=\dfrac{-5}{10}=\dfrac{-1}{2}\)

30 tháng 1 2023

\(\left(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+...+\dfrac{1}{10}\right)\) . x = \(\dfrac{1}{9}+\dfrac{2}{8}+\dfrac{3}{7}+...+\dfrac{9}{1}\)

Biến đổi vế phải 

\(\dfrac{1}{9}+\dfrac{2}{8}+\dfrac{3}{7}+...+\dfrac{9}{1}\) 

\(\left(\dfrac{1}{9}+1\right)+\left(\dfrac{2}{8}+1\right)+\left(\dfrac{3}{7}+1\right)+...+\left(\dfrac{8}{2}+1\right)+1\)   

\(\dfrac{10}{10}+\dfrac{10}{9}+\dfrac{10}{8}+\dfrac{10}{7}+...+\dfrac{10}{2}\)

\(10\left(\dfrac{1}{10}+\dfrac{1}{9}+\dfrac{1}{8}+...+\dfrac{1}{2}\right)\)

⇒ x = 10