Vd1: 

d) Ta có: \(\sqrt{2}\left(x-1\right)-\sqrt{50}=0\)

\(\Leftrightarrow\sqrt{2}\left(x-1-5\right)=0\)

\(\Leftrightarrow x=6\)

-25-(x+5) = 415 + 5(x-83)

=> -25-x-5=415+5x-415

=> -30-x-5x = 0

=> -30=6x

=> x = -5 

`-25-(x+5)=415+5(x-83)`

`<=> -25-x-5=415+5x-415`

`<=> -x-5x=415-415+25+5`

`<=> -6x=30`

`<=> x=-5`

-25 - ( x+5 ) = 415 + 5(x- 83)

\(-25-x-5-415-5x+415=0\)

\(-30-6x=0\)

\(6x=-30\)

\(x=-30:6=-5\)

Vậy x=-5

Bạn vô đó để viết lại đề nha!

Bạn gõ bằng công thức trực quan để được giúp đỡ nhanh hơn nhé, chứ mình nhìn thế không dịch được (Nhấp vào biểu tượng chữ M nằm ngang)

a) PTHH: \(Na+H_2O\rightarrow NaOH+\dfrac{1}{2}H_2\uparrow\)

b+c+d) Ta có: \(n_{Na}=\dfrac{4,6}{23}=0,2\left(mol\right)\)

\(\Rightarrow\left\{{}\begin{matrix}n_{NaOH}=0,2\left(mol\right)\\n_{H_2}=0,1\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{NaOH}=0,2\cdot40=8\left(g\right)\\V_{H_2}=0,1\cdot22,4=2,24\left(l\right)\\m_{H_2}=0,1\cdot2=0,2\left(g\right)\end{matrix}\right.\)

Mặt khác: \(m_{dd\left(saup/ứ\right)}=m_{Na}+m_{H_2O}-m_{H_2}=204,4\left(g\right)\)

\(\Rightarrow C\%_{NaOH}=\dfrac{8}{204,4}\cdot100\%\approx3,91\%\)

a, \(2Na+2H_2O\rightarrow2NaOH+H_2\)

200 (ml hay l) dung dịch nước ạ?

\(R_{13}=\dfrac{4\cdot2}{4+2}=\dfrac{4}{3}\Omega\)

\(R_N=\dfrac{\dfrac{4}{3}\cdot6}{\dfrac{4}{3}+6}=\dfrac{12}{11}\Omega\)

\(U_{AB}=12+8=20V\)

\(I=\dfrac{U}{R}=\dfrac{20}{\dfrac{12}{11}}=\dfrac{55}{3}A\)

\(I_{13}=I_m=\dfrac{55}{3}A\Rightarrow U_{13}=\dfrac{55}{3}\cdot\dfrac{4}{3}=\dfrac{220}{9}V\)

\(\Rightarrow U_3=\dfrac{220}{9}V\Rightarrow I_3=\dfrac{U_3}{R_3}=\dfrac{\dfrac{220}{9}}{2}=\dfrac{110}{9}A\)

I.Hãy viết hình thức so sánh hơn và nhất của các tính từ sau:

1. So sánh ngang bằng.

a. Mary/tall/her brother.

Mary is as tall as her brother.

b. A lemon/not sweet/ an orange. 

A lemon is not as sweet as an orange.

c. A donkey/not big/ a horse.

A donkey is not as big as a horse.

d. This dress/pretty/that one.

This dress is not as pretty as that one.

e. the weather/not cold/ yesterday.

The weather is not as cold as yesterday.

2. So sánh hơn: (Nhấn mạnh các câu ss hơn)

a. A rose/beautiful/ a weed.

A rose is more beautiful than a weed.

b. A dog/run/quick/ a chicken.

A dog runs more quickly than a chicken.

c. Ba/ friendly/ Nam.

Ba is more friendly than Nam.

d .Your house/far/from school /my house.

Your house if farther from school than my house_.

e. My father / drive/ careful/ I

My father drives more carefully than I do.

3. So sánh nhất:

a. The Nile/long/river/ in the world.

The Nile is the longest river in the world.

b. Lan/ talk/ slow / in my class.

Lan talks the most slowly in my class.

c. English coffee/bad/ of all.

English coffee is the worst of all.

d. Anna/ is/ simple/girl/ in the world.

Anna is the simplest girl in the world.

e. That/high/ mountain in the world.

That is the highest mountain in the world.

II. Complete the sentences using the correct form of the adjectives or adverbs in brackets

(chia về các dạng so sánh đúng)

1. Mary is (pretty) as pretty as her sister

2. A new house is (expensive) more expensive than an old one

3. His job is (important) more important than mine

4. Of the foour ties, I like the red one (well) better

5. Nobody is (happy) happier than Miss Snow

6. Today English is the (international) most international of language

7. John is much (strong) stronger than I thought

8. Benches are (comfortable) more comfortable than arm-chairs

9. Bill is (good) better than you thought

10. Mr. Bush is the (delightful) most delightful person I have ever know

11. Bill is (lazy) lazier and (lazy) lazier.

12. It becomes (hard) harder and (hard) harder to find a job

13. As the conversation went on, he became (talkative) more and more talkative.

14. As I waited for my interview, I became (nervous) more and more nervous.

5. Is the book (interesting) more interesting than the one you read last week?

III. Cirle the best option to complete each sentence:

1. This is the _________ river in the world

a. most long               b. longest                   c. long most               d. longer

2. Do you think older people drive _________ than younger people?

a. slow                                    b. slower                    c. more slow              d. more slowly

3. They all dance well, but John dances _________

a. better                      b. more good             c. the better               d. the best

4. Your computer is more expensive than _________

a. me                           b. my                          c. mine                                   d. myself

5. My car isn’t very new. Your car is _____ than my car

a. newer                     b. older                       c. not new                  d. less new

6. Who is _____ in your class?

a. the interlligentest                                     b. the most intelligent                     

c. more intelligent                                        d. the more intelligent

7. Praja returned home as _________ as he could

a. quick                      b. quicker                  c. quickest                 d. quickly

8. This is _________ elephant I have ever seen

a. the biggest             b. most big                 c. the most big                       d. bigger

9. He ran _________ than his friend

a. fastest                     b. faster                      c. fast                          d. more fast

10. This summer is not as hot _________ last summer

a. as                            b. than                        c. to                             d. like

11. “Could you talk _________ ? I’m learning my lessons”

a. as quietly               b. so quietly              c. more quietly          d. most quietly

12. It is _________ to talk about a problem than to solve it

a. more easier                        b. easier                     c. easy                        d. easiest

13 Jim is five centimeters _________ than Tom

a. higher                     b. taller                       c. tallest                     d. tall

14. Winning a place at university _________ for most students

a. has become as difficult                           b. becomes the most difficulty

c. is becoming more and more difficult    d. will become more difficult

15. The people here are _________ than I expected

a. more nice               b. most nice               c. nicer                                   d. nicest

16. My new boss isn’t as rude _________ my own boss

a. as                            b. so                            c. than                        d. that

20. She was _________ friendly person I’ve ever met

a. the most          b.more                      c.as             d. so

I.Hãy viết hình thức so sánh hơn và nhất của các tính từ sau:

1. So sánh ngang bằng.

a. Mary/tall/her brother.

_____Mary is as tall as her brother__________________________________________

b. A lemon/not sweet/ an orange. 

______A lemon is not as sweet as an orange_________________________________________

c. A donkey/not big/ a horse.

_____A donkey is not as big as a horse__________________________________________

d. This dress/pretty/that one.

_______THis dress is not as pretty as that one________________________________________

e. the weather/not cold/ yesterday.

_______The weather is not as cold as yesterday________________________________________

2. So sánh hơn: (Nhấn mạnh các câu ss hơn)

a. A rose/beautiful/ a weed.

______A rose is more beautiful than a weed_________________________________________

b. A dog/run/quick/ a chicken.

_____A dog runs more quickly than a chicken__________________________________________

c. Ba/ friendly/ Nam.

_______Ba is more friendly than Nam________________________________________

d .Your house/far/from school /my house. ______Your house if farther from school than my house_________________________________________

e. My father / drive/ careful/ I

_______My father drives more carefully than I do________________________________________

3. So sánh nhất:

a. The Nile/long/river/ in the world.

___The Nile is the longest river in the world____________________________________________

b. Lan/ talk/ slow / in my class.

____Lan talks the most slowly in my class___________________________________________

c. English coffee/bad/ of all.

______English coffee is the worst of all_________________________________________

d. Anna/ work/ simple/girl/ in the world. ___Anna works the most somple girl in the world____________________________________________

e. That/high/ mountain in the world.

____That is the highest mountain in the world___________________________________________

II. Complete the sentences using the correct form of the adjectives or adverbs in brackets

(chia về các dạng so sánh đúng)

1. Mary is (pretty) _______as pretty _________ as her sister

2. A new house is (expensive) _____more expensive___________ than an old one

3. His job is (important) _______more important_________ than mine

4. Of the foour ties, I like the red one (well) _______better_________

5. Nobody is (happy) _____happier___________ than Miss Snow

6. Today English is the (international) _______most international_________ of language

7. John is much (strong) ________stronger________ than I thought

8. Benches are (comfortable) ______more comfortable __________ than arm-chairs

9. Bill is (good) ______better__________ than you thought

10. Mr. Bush is the (delightful) ______most delightful__________ person I have ever know

11. Bill is (lazy) _______lazier_________ and (lazy) ___lazier_____________

12. It becomes (hard) ______harder__________ and (hard) _____harder___________ to find a job

13. As the conversation went on, he became (talkative) ________more and more talkative________

14. As I waited for my interview, I became (nervous) _______more and more nervous_________

15. Is the book (interesting) ________more interesting________ than the one you read last week?

III. Cirle the best option to complete each sentence:

1. This is the _________ river in the world

a. most long               b. longest                   c. long most               d. longer

2. Do you think older people drive _________ than younger people?

a. slow                                    b. slower                    c. more slow              d. more slowly

3. They all dance well, but John dances _________

a. better                      b. more good             c. the better               d. the best

4. Your computer is more expensive than _________

a. me                           b. my                          c. mine                                   d. myself

5. My car isn’t very new. Your car is _____ than my car

a. newer                     b. older                       c. not new                  d. less new

6. Who is _____ in your class?

a. the interlligentest                                     b. the most intelligent                     

c. more intelligent                                        d. the more intelligent

7. Praja returned home as _________ as he could

a. quick                      b. quicker                  c. quickest                 d. quickly

8. This is _________ elephant I have ever seen

a. the biggest             b. most big                 c. the most big                       d. bigger

9. He ran _________ than his friend

a. fastest                     b. faster                      c. fast                          d. more fast

10. This summer is not as hot _________ last summer

a. as                            b. than                        c. to                             d. like

11. “Could you talk _________ ? I’m learning my lessons”

a. as quietly               b. so quietly              c. more quietly          d. most quietly

12. It is _________ to talk about a problem than to solve it

a. more easier                        b. easier                     c. easy                        d. easiest

13 Jim is five centimeters _________ than Tom

a. higher                     b. taller                       c. tallest                     d. tall

14. Winning a place at university _________ for most students

a. has become as difficult                           b. becomes the most difficulty

c. is becoming more and more difficult    d. will become more difficult

15. The people here are _________ than I expected

a. more nice               b. most nice               c. nicer                                   d. nicest

16. My new boss isn’t as rude _________ my own boss

a. as                            b. so                            c. than                        d. that

20. She was _________ friendly person I’ve ever met

a. the most          b.more                      c.as             d. so

y=2x 

x=0=> y=0 => A(0;0)

x=1 => y=2 => B(1;2)

=> đồ thị y=2x đi qua A(0;0) và B(1;2)

cái kia làm tương tự 

\(\left(\dfrac{1}{2}-\dfrac{x}{3}\right)^2=\dfrac{36}{49}\\ \Rightarrow\left(\dfrac{1}{2}-\dfrac{x}{3}\right)^2=\left(\dfrac{6}{7}\right)^2\\ \Rightarrow\dfrac{1}{2}-\dfrac{x}{3}=\pm\dfrac{6}{7}\\ \Rightarrow\left[{}\begin{matrix}\dfrac{1}{2}-\dfrac{x}{3}=\dfrac{6}{7}\\\dfrac{1}{2}-\dfrac{x}{3}=-\dfrac{6}{7}\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}\dfrac{x}{3}=-\dfrac{5}{14}\\\dfrac{x}{3}=\dfrac{19}{14}\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=-\dfrac{5}{14}\times3\\x=\dfrac{19}{14}\times3\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=-\dfrac{15}{14}\\x=\dfrac{57}{14}\end{matrix}\right.\)

\(\left(3-\dfrac{2}{3}x\right)^3=-\dfrac{1}{64}\\ \Rightarrow\left(3-\dfrac{2}{3}x\right)^3=\left(-\dfrac{1}{4}\right)^3\\ \Rightarrow3-\dfrac{2}{3}x=-\dfrac{1}{4}\\ \Rightarrow\dfrac{2}{3}x=3-\left(-\dfrac{1}{4}\right)\\ \Rightarrow\dfrac{2}{3}x=\dfrac{13}{4}\\ \Rightarrow x=\dfrac{13}{4}:\dfrac{2}{3}\\ \Rightarrow x=\dfrac{13}{4}\times\dfrac{3}{2}\\ \Rightarrow x=\dfrac{39}{8}\)