29: 

uses crt;

var n,i,j,kt:integer;

a:array[1..100]of integer;

begin

clrscr;

readln(n);

for i:=1 to n do

readln(a[i]);

for i:=1 to n do

if a[i]>1 then 

begin

kt:=0;

for j:=2 to trunc(sqrt(a[i])) do

if a[i] mod j=0 then kt:=1;

if kt=0 then write(a[i]:4);

end;

readln;

end.

\(f'\left(x\right)=\dfrac{-3}{\left(x-1\right)^2}\) ; \(f''\left(x\right)=\dfrac{6}{\left(x-1\right)^3}\)

\(f'\left(x\right)+f''\left(x\right)=0\Leftrightarrow\dfrac{-3}{\left(x-1\right)^2}+\dfrac{6}{\left(x-1\right)^3}=0\) (\(x\ne1\))

\(\Leftrightarrow-3\left(x-1\right)+6=0\Rightarrow x=3\)

28)

$n_{CO_2} = \dfrac{6,72}{22,4} = 0,3(mol)$
$n_{H_2O} = \dfrac{9,9}{18} = 0,55(mol)$

Ta thấy : $n_{H_2O} > n_{CO_2} \to$ Ancol no

$\Rightarrow n_{O\ trong\ X} = n_{OH} = n_{H_2O} - n_{CO_2} = 0,25(mol)$

$\Rightarrow m_X = m_C + m_H + m_O = 0,3.12 + 0,55.2 + 0,25.16 = 8,7(gam)$

Khi ete hóa : $n_{H_2O} = \dfrac{1}{2}n_{OH} = 0,125(mol)$

$\Rightarrow m_{ete} = m_X - m_{H_2O} = 8,7 - 0,125.18 = 6,45(gam)$

Đáp án A

29)

$n_{CO_2} = 0,3(mol) ; n_{O_2} = 0,35(mol)$

Bảo toàn C :

$n_C = n_{CO_2} = 0,3(mol)$
Số nguyên tử C = $\dfrac{n_C}{n_X} = \dfrac{0,3}{0,1} = 3$

Loại : đáp án A

X là ancol no $\to n_{H_2O} - n_{CO_2} = n_X \Rightarrow n_{H_2O} = 0,4(mol)$
$\Rightarrow n_H = 2n_{H_2O} = 0,8(mol)$

Số nguyên tử H $= \dfrac{n_H}{n_X} = 8$

Bảo toàn nguyên tố C : 

$n_{OH} + 2n_{O_2} = 2n_{CO_2} + n_{H_2O} \to n_{OH} = 0,2$

Số nhóm $OH = \dfrac{n_{OH}}{n_X} = 2$

Vậy CT của X là $C_3H_6(OH)_2$

Anh chưa thấy ndung câu hỏi em ạ

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4 The woman to whom you gave place on the bus lives next door to me

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6 THe girl with whom I went on holiday is so cute

7 The city in which my grandmother live seems to be quiet

8 It is the shop in which my sister works

9 They are the interesting books for which I have been looking

10 The picnic to which I went yesterday morning was really exciting

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16 The college at which we used to study was large with a large ground

17 Mrs Hoa, about whom the students are talking, is very lovely and gentle

18 The villa in which they lived is not only beautiful but also very modern

19 Mr Vu, with whom I made friend, is a handsome and strong man

20 The novel about which I told you is about the adventure of a cricket

21 The widow with whom my brother fell in love is very pretty

22 Mrs Hoa and Mrs Quyen, with whom I work, teach English very well

23  Ha Noi, in which we are going to live, is a beautiful city

24 The crash about which I and my friends are talking is really terrible

25 Bach Ma National Park, in which many kind of rare animal are living, is very beautiful

26 The banquat to which we went yesterday was very delicious

27 The banchelor to whom I talked last night was very kind

28 The flat in which we used to live was large with a green garden

29 Nam, with whom I learn in the same class, is a good student