Trả lời :

\(\frac{72^3.542}{108^4}\)= \(\frac{202300416}{136048896}\)

P/s : Bn tự rút gọn nha

:D

72³ x 542 = 202300416

108⁴ = 136048896

\(\frac{72^3\times542}{108^4}\)

\(=\frac{202300416}{136048896}\)

\(=\frac{1084}{729}\)

\(\frac{x}{2}=\frac{2y}{3}=\frac{3z}{4}=>\frac{x}{2}.\frac{2y}{3}.\frac{3z}{4}=\frac{x}{2}.\frac{x}{2}.\frac{x}{2}\)

=>\(\frac{x.2y.3z}{2.3.4}=\frac{x^3}{2.2.2}\)

=>\(\frac{xyz.6}{24}=\frac{x^3}{8}\)

=>\(\frac{x^3}{8}=\frac{108.6}{24}\)

=>\(\frac{x^3}{8}=27\)

=>\(x^3=27.8=>x^3=216=6^3=>x=6\)

Đáp án là D

\(m_{CuCl_2}=0,5.135=67,5\left(g\right)\\ C\%_{CuCl_2}=\dfrac{67,5}{542}.100\%=12,45\%\)

`m_[CuCl_2] = 0,5 . 135 = 67,5 (g)`

`-> C%_[CuCl_2] = [ 67,5 ] / 542 . 100 ~~ 12,45 %`

\(\frac{72^3.54^2}{108^4}=\frac{108^4.8}{108^4}=8\)

B = \(\frac{6272}{729}\)

a) Cửa hàng còn :

  42 - \(\frac{1}{6}\)x 42 = 35 ( cái áo )

                       Vậy , ....

b) Số áo bán đi bằng : 

  \(\frac{\frac{1}{6}x42}{35}\)\(=\) \(\frac{7}{35}=\frac{1}{5}\)

                           Vậy ,...

(542 - 541)²⁹³⁸ = 1²⁹³⁸ = 1

(542 + 541)⁰ = 1083⁰ = 1

Vậy : (542  - 541)²⁹³⁸ = (542 + 541)⁰ (đpcm)

=

2: 

#include <bits/stdc++.h>

using namespace std;

long long x,n,i,dem,t;

int main()

{

cin>>n;

t=0;

for (i=1; i<=n; i++)

{

cin>>x;

if (x%3==0) t=t+x;

}

cout<<t;

return 0;

}

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