7 x 3,8  : x+ 57 - 3 x 19 = 1,75

26,6     : x+ 57 -    57    = 1,75

  26,6   : x+   0               =1,75

  26,6   : x                      =1,75 - 0

  26,6      :x                       =1,75

             x                       =1,75 * 26,6

             x                       =46,55

Tick mình  nha***

Bài 1:

b) \(71+65.4=\frac{x+140}{x}+260\)

\(\Rightarrow331=\frac{x+140}{x}+260\)

\(\Rightarrow\frac{x+140}{x}=71\)

\(\Rightarrow x+140=71x\)

\(\Rightarrow71x-x=140\)

\(\Rightarrow70x=140\)

\(\Rightarrow x=2\)

Vậy ...

c) \(7:\left(\frac{3,8.x}{19}+3\right)=1,75\)

 \(\frac{3,8.x}{19}+3=4\)

\(\frac{3,8.x}{19}=1\)

\(3,8.x=19\)

\(x=5\)

vaayj ...

#)Góp ý :

Câu a) hình như bn chép sai rùi thì ph nhỉ ???

Dãy số này cách đều nhau 3 đơn vị tính từ x + 1 thì sao có x + 17 ; x + 20 được ???

\(7:\left(\frac{3,8\times x-57}{19}+3\right)=1,75\)

=> \(\frac{3,8\times x-57}{19}+3=7:1,75\)

=> \(\frac{3,8\times x-57}{19}+3=4\)

=> \(\frac{3,8\times x-57}{19}=4-3=1\)

=> \(3,8\times x-57=19\)

=> \(3,8\times x=19+57=76\)

=> \(x=76:3,8=20\)

Vậy x = 20.

Bạn cho minh cách lam duoc k

\(7:\left(\dfrac{3,8\times y-57}{19}+3\right)=1,75\)

\(\Rightarrow\left(\dfrac{3,8\times y-57}{19}+3\right)=7:1,75\)

\(\Rightarrow\dfrac{3,8\times y-57}{19}+3=4\)

\(\Rightarrow\dfrac{3,8\times y-57}{19}=4-3\)

\(\Rightarrow\dfrac{3,8\times y-57}{19}=1\)

\(\Rightarrow3,8\times y-57=1\times19\)

\(\Rightarrow3,8\times y-57=19\)

\(\Rightarrow3,8\times y=19+57\)

\(\Rightarrow3,8\times y=76\)

\(\Rightarrow y=76:3,8\)

\(\Rightarrow y=20\)

\(7\left[\frac{\left(3,8x-57\right)}{19}+3\right]=1,75\Leftrightarrow x=\frac{\left[\left(\frac{1,75}{7}-3\right)\cdot19+57\right]}{3,8}=1,25\)

Vậy x = 1,25