3 hostages have been kept by this terrorist for a week

I will be picked up at my house by my father

 I will be taken to HCMC next week by my father

31.3 hostages have been hept by this terrorist for a week

32.I will be picked up at my house by them

33.I will be taken to Ho Chi Minh city by my father next week.

Chúc em học tốt

31.3 hostages were held by the terrorist in a week.

32.I will be picked up by them at my house.

33.I will be brought to HCMC by my father next week.

\(\sqrt{9-3\sqrt{5}}-\sqrt{9+3\sqrt{5}}=\dfrac{1}{\sqrt{2}}\left(\sqrt{18-6\sqrt{5}}-\sqrt{18+6\sqrt{5}}\right)\)

\(=\dfrac{1}{\sqrt{2}}\left(\sqrt{\left(\sqrt{15}-\sqrt{3}\right)^2}-\sqrt{\left(\sqrt{15}+\sqrt{3}\right)^2}\right)\)

\(=\dfrac{1}{\sqrt{2}}\left(\sqrt{15}-\sqrt{3}-\sqrt{15}-\sqrt{3}\right)=-\dfrac{2\sqrt{3}}{\sqrt{2}}=-\sqrt{6}\)

\(\sqrt{4-\sqrt{15}}+\sqrt{4+\sqrt{15}}-2\sqrt{3-\sqrt{5}}\)

\(=\dfrac{1}{\sqrt{2}}\left(\sqrt{8-2\sqrt{15}}+\sqrt{8+2\sqrt{15}}-2\sqrt{6-2\sqrt{5}}\right)\)

\(=\dfrac{1}{\sqrt{2}}\left(\sqrt{\left(\sqrt{5}-\sqrt{3}\right)^2}+\sqrt{\left(\sqrt{5}+\sqrt{3}\right)^2}-2\sqrt{\left(\sqrt{5}-1\right)^2}\right)\)

\(=\dfrac{1}{\sqrt{2}}\left(\sqrt{5}-\sqrt{3}+\sqrt{5}+\sqrt{3}-2\left(\sqrt{5}-1\right)\right)\)

\(=\dfrac{2}{\sqrt{2}}=\sqrt{2}\)

k: Ta có: \(\sqrt{9-3\sqrt{5}}-\sqrt{9+3\sqrt{5}}\)

\(=\dfrac{\sqrt{18-6\sqrt{5}}-\sqrt{18+6\sqrt{5}}}{\sqrt{2}}\)

\(=\dfrac{\sqrt{15}-\sqrt{3}-\sqrt{15}-\sqrt{3}}{\sqrt{2}}\)

\(=-\sqrt{6}\)

e.

$\frac{8}{23}.\frac{46}{24}=\frac{1}{3}x$

$\frac{2}{3}=\frac{1}{3}x$

$x=\frac{2}{3}: \frac{1}{3}=2$

f.

$\frac{1}{5}:x=\frac{1}{5}-\frac{1}{7}=\frac{2}{35}$

$x=\frac{1}{5}: \frac{2}{35}=\frac{7}{2}$

g.

$\frac{4}{9}-(x-\frac{1}{2})^2=\frac{1}{3}$

$(x-\frac{1}{2})^2=\frac{4}{9}-\frac{1}{3}=\frac{1}{9}=(\frac{1}{3})^2=(\frac{-1}{3})^2$

$\Rightarrow x-\frac{1}{2}=\frac{1}{3}$ hoặc $x-\frac{1}{2}=\frac{-1}{3}$
$\Rightarrow x=\frac{1}{3}+\frac{1}{2}=\frac{5}{6}$ hoặc $x=\frac{-1}{3}+\frac{1}{2}=\frac{1}{6}$

h.

$3,2x-(\frac{4}{5}+\frac{2}{3}):3\frac{2}{3}=\frac{7}{20}$

$3,2x-\frac{2}{5}=\frac{7}{20}$

$3,2x=\frac{7}{20}+\frac{2}{5}=\frac{3}{4}$

$x=\frac{3}{4}: 3,2=\frac{15}{64}$

i.

$(4\frac{1}{2}-2x).1\frac{4}{61}=6\frac{1}{2}$

$(\frac{9}{2}-2x).\frac{65}{61}=\frac{13}{2}$

$\frac{9}{2}-2x=\frac{13}{2}: \frac{65}{61}=\frac{61}{10}$

$2x=\frac{9}{2}-\frac{61}{10}=\frac{-8}{5}$

$x=\frac{-8}{5}:2 =\frac{-4}{5}$

a.

$\frac{5}{7}-\frac{3}{7}x=1$

$\frac{3}{7}x=\frac{5}{7}-1=\frac{-2}{7}$

$x=\frac{-2}{7}: \frac{3}{7}=\frac{-3}{2}$

b.

$x-\frac{-3}{4}=\frac{-14}{25}$

$x=\frac{-14}{25}+\frac{-3}{4}=\frac{-131}{100}$

c.

$\frac{-5}{20}-x=\frac{-7}{5}$

$x=\frac{-5}{20}-\frac{-7}{5}=\frac{23}{20}$

d.

$x+\frac{3}{4}=\frac{36}{144}.\frac{-12}{9}=\frac{-1}{3}$
$x=\frac{-1}{3}-\frac{3}{4}=\frac{-13}{12}$

a: =>3/7x=-2/7

=>x=-2/3

b: =>x=-14/25+3/4=-56/100+75/100=21/100

c: =>-1/4-x=-7/5

=>x+1/4=7/5

=>x=7/5-1/4=28/20-5/20=23/20

d: =>x+3/4=1/4*(-4/3)=-1/3

=>x=-1/3-3/4=-4/12-9/12=-13/12

e: =>x*1/3=46/23*8/24=2*1/3=2/3

=>x=2

f: =>1/5:x=2/35

=>x=1/5:2/35=1/5*35/2=35/10=7/2

g: =>(x-1/2)^2=4/9-1/3=1/9

=>x-1/2=1/3 hoặc x-1/2=-1/3

=>x=5/6 hoặc x=-1/6

h: =>3,2x=3/4

=>16/5x=3/4

=>x=3/4:16/5=3/4*5/16=15/64

i: =>(4,5-2x)=6,1

=>2x=-1,6

=>x=-0,8

Câu 31: A

Câu 32: C

Câu 33: D

Câu 34: B

Câu 35: C

Chọn D

31 The door will be shut if you like

32 A horrible accident has just been seen by us

33 What language is spoken in this country?

34 At 7 p.m, cakes are were being made

35 THat house isn't going to be bought

37 You haven't been seen for years

38 The passage will be read 3 times by the examiner

39 The town was destroyed by an earthquake

40 THe letter wasn't typed by him last light

41 I will be picked up at my house

42 When was he seen in that bank by you?

43 The keys were returned to me by a man

44 Her friends will be seen off by Mary  at the station

45 That building has to be pullled down

46 I was given a knife by him to cut this bread

.31. I will shut the door if you like.

=> The door will be shut if you like.

32. We have just seen a horrible accident

=> A horrible accident has just been seen.

 33. What language do people speak in this country?

=> What language is spoken in this country?

 34. At 7 p.m., Mrs. Smith was making cakes.

=> Cakes were being made by Mrs. Smith at 7p.m.

 35. He isn’t going to buy that house

=> That house isn't going to be bought by him.

.36. This terrorist has kept 3 hostages for a week.

=> 3 hostages have been kept by this terrorist for a week.

37. He hasn’t seen you for years.

=> You haven't been seen by him for years.

 38. The examiner will read the passage 3 times.

=> The passage will be read 3 times by the examiner.

39. An earthquake destroyed the town.

=> The town was destroyed by an earthquake.

40. He didn’t type the letter last night.

=> The letter wasn't typed by him last night.

 41. They will pick me up at my house.

=> I was picked up at my house.

 42. When did you see him in that bank?

=> When was he seen in that bank?

 43. A man returned the keys to me.

=> The keys were returned to me.

 44. Mary will see her friends off at the station.

=> Her friends will be seen off at the station by Mary.

 45. They have to pull down that building.

=> That building has to be pulled down.

 46. He gave me a knife to cut this bread.

=> A kinfe was given to me to cut this bread.

tui muốn kb nhoa 

tui muốn kb nha

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\(\Leftrightarrow3B=3^2+3^3+...+3^{101}\\ \Leftrightarrow3B-B=3^{101}-3\\ \Leftrightarrow2B=3^{101}-3\\ \Leftrightarrow2B+3=3^{101}=3^n\\ \Leftrightarrow n=101\)