Em muốn viết PTHH minh họa hả?

2Al + 6 HCl -> 2 AlCl3 + 3H2

Mg +2 HCl -> MgCl2 + H2

Zn + H2SO4 -> ZnSO4 + H2

Fe + H2SO4 -> FeSO4 + H2

2Al +3 H2SO4 -> Al2(SO4)3+ 3 H2

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Huyy
47 phút trước

GIÚP E BÀI 1

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Huyy
46 phút trước

TRÌNH BÀY ĐẦY ĐỦ CÁC BƯỚC. KO BỎ BƯỚC

 

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Bài 1:

a) \(x^2+4x+4=\left(x+2\right)^2\)

b) \(x^2y^2-6xy+9=\left(xy-3\right)^2\)

c) \(x^4-16y^2=\left(x^2-4y\right)\left(x^2+4y\right)\)

d) \(81-y^4=\left(9-y^2\right)\left(9+y^2\right)=\left(y^2+9\right)\left(3-y\right)\left(3+y\right)\)

e) \(125x^3-8=\left(5x-2\right)\left(25x^2+10x+4\right)\)

f) \(x^3-3x^2+3x-1=\left(x-1\right)^3\)

g) \(1+9x+27x^2+27x^3=\left(1+3x\right)^3\)

h) \(64x^3+1=\left(4x+1\right)\left(16x^2-4x+1\right)\)

i) \(216x^3-125=\left(6x-5\right)\left(36x^2+30x+25\right)\)

k) \(x^2+10x+25=\left(x+5\right)^2\)

l) \(49-36y^2=\left(7-6y\right)\left(7+6y\right)\)

m) \(9x^2-x+\dfrac{1}{36}=\left(3x-\dfrac{1}{6}\right)^2\)

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Lazyboy
48 phút trước

1 personality

2 terrorists

3 unexpectedly

4 uncomfortable

5 beneficial 

6 asleep

7 instructions

8 anxiety

9 enthusiasm

10 refusal 

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Khinh Yên
46 phút trước

personality

terrorists

unexpectedly

discomfort

beneficial 

asleep

instructions

anxiety

enthusiasm

refusal 

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Lazyboy
1 giờ trước (18:13)

Use the suggested words and phrases to make complete sentences. (10 pts)

1. Margaret/ not/ apply/ job/ library/ and/ regret it/ now 

Margater didn't apply for the job in the library and he regrets it now

2. Unless/ you/ hurry/ you/ not/ able/ catch/ train.

Unless you hurry, you won't be able to catch the train

3. Castle/ build/ 17th century? 

Was this castle built in the 17th century?

4. Children/ very fond/ play/ rain. 

Children are very fond of playing in the rain

5. He/ most intelligent boy/ I/ ever/ meet. 

He is the most intelligent boy I have ever met

6. He/ now/ work/ mechanic/ car factory. 

He is now working as a mechanic in a car factory

7. You/ like/ spend/ free time/ play badminton/ me?

Would you like to spend your free time playing badminton with me

8. If/ he/ give up/ smoke/ health/ become/ better/ better. 

If he gives up smoking, his health will become better and better

9. We/ bored/ eat/ same food/ every day. 

We are bored with eating the same food everyday

10. They/ decide/ go/ beach/although/ it/ rain/ hard.

They decided to go to the beach although it was raining hard

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Khinh Yên
60 phút trước

Use the suggested words and phrases to make complete sentences. (10 pts)

1. Margaret/ not/ apply/ job/ library/ and/ regret it/ now Maria didn’t apply for the job in the library and regrets it now

2. Unless/ you/ hurry/ you/ not/ able/ catch/ train. unless you hurry ,we won't be able to catch the train

3. Castle/ build/ 17th century? Was the castle built in 17th century?

4. Children/ very fond/ play/ rain. The children are very fond of playing in the rain

5. He/ most intelligent boy/ I/ ever/ meet. He is the most intelligent boy I’ve ever met. 

6. He/ now/ work/ mechanic/ car factory. He is now working as a mechanic in a car factory

7. You/ like/ spend/ free time/ play badminton/ me? Do you like spending your free time playing badminton with me?

8. If/ he/ give up/ smoke/ health/ become/ better/ better. If he gives up smoking, his health will become better and better

9. We/ bored/ eat/ same food/ every day. We are bored with eating the same food everyday

10. They/ decide/ go/ beach/although/ it/ rain/ hard. They decided to go to the beach although it was raining hard

 

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Anh Minh

Bài 2: 

a) \(4x^2-4xy+y^2=\left(2x-y\right)^2\)

b) \(25y^2-9x^2=\left(5y-3x\right)\left(5y+3x\right)\)

c) \(9x^2+6xy+y^2=\left(3x+y\right)^2\)

d) \(16x^2+40xy+25y^2=\left(4x+5y\right)^2\)

e) \(x^2-x+\dfrac{1}{4}=\left(x-\dfrac{1}{2}\right)^2\)

f) \(\dfrac{1}{4}x^2+x+1=\left(\dfrac{1}{2}x+1\right)^2\)

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Dương Hải
1 giờ trước (18:00)

`Δ=1^2-4.1.(-7)=29>0`

`->\sqrt{Δ}=\sqrt{29}`

Vậy phương trình có 2 nghiệm phân biệt

`x_1=(-1+\sqrt{29})/2`

`x_2=(-1-\sqrt{29})/2`

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\(\Delta=1^2-4\cdot3\cdot\left(-7\right)=85\)

Vì \(\Delta>0\) nên phương trình có hai nghiệm phân biệt là:

\(\left\{{}\begin{matrix}x_1=\dfrac{-1-\sqrt{85}}{6}\\x_2=\dfrac{-1+\sqrt{85}}{6}\end{matrix}\right.\)

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Khinh Yên
1 giờ trước (17:52)

Give the correct form or tense of the verbs in brackets. 

It's difficult (make)to make her (change)change her mind.

They (live)have been living happily for over 20 years now. Since their marriage they (never have)have never had an argument.

I (talk)will talk to you about that matter as soon as the meeting (finish)finishes, OK?

Did you remember (send) sending your uncle a card when you (be) were on holiday?

My father would rather I (study)studied medicine when I finish school, but I’d prefer (become)to become a teacher.

Now I (feel)feel as if I (sit)were sitting on fire. If it (not rain)didn't rain so much, we (have)would have a better crop.

We (have)are going to have our house (repaint) repainted next month.

When I (pass) passed by her house, I saw her (water)watering the flowers.

 

I (meet)met Tom last Sunday when I (look) was looking for some books in the city centre.

 

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Lazyboy
1 giờ trước (17:54)

1 to make - change

2 have been living - have never had

3 will talk - finishes 

4 sending - were

5 studied - to become

6 feel -am sitting - didn't rain - would have

7 will have - repainted

8 passed - watering

9 met - was looking 

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Khinh Yên
2 giờ trước (17:38)

refer

1.       Ronald is very good _______at_________ speaking _______in_________ public.

2.       The train arrived _________at_______ the station ________at________ exactly 6pm.

3.       She enjoys looking _________at_______ the sky _________in_______ hot summer nights.

4.       They often quarrel ______over__________ each other ___________about_____ little things.

5.       I’ll have to complain __________to______ the manager ______about__________ the bad service here.

6.       John is very ashamed __________of______ his attitude ________ toward________ his neighbours.

7.       _______on_________ average, she spends $20 _______on_________ books and records a month.

8.       ____from____________ time _______to_________ time they eat at a Chinese restaurant.

9.       Many species of birds leave their nests __________at______ dawn and come back ________by________ dusk.

 

10.    ____________in____ the early morning, the temperature on the mountain may fall ________below________ zero.

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Lazyboy
2 giờ trước (17:42)

1 at - in

2 in - at

3 at - at

4 with - about

5 to - about

6 of - towards

7 On - on

8 from - to

9 at - by

10 In - below

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