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Câu 3: Xét \(\Delta ABC\) vuông tại A

Ta có: \(AH^2=BH.HC\left(HTL2\right)\Rightarrow HC=\dfrac{12^2}{9}=16\left(cm\right)\)

\(S\Delta ABC=\dfrac{1}{2}\cdot AH.BC=\dfrac{1}{2}.12.\left(9+16\right)=150\left(cm^2\right)\)

Câu 2: a) Xét \(\Delta ABC\) vuông tại A

Ta có: \(AH^2=BH.HC\left(HTL2\right)\Rightarrow HC=\dfrac{6^2}{4,5}=8\left(cm\right)\)

\(BC=BH+HC=4,5+8=12,5\left(cm\right)\)

Lại có: \(AB^2=BC.BH\left(HTL1\right)\Rightarrow AB=\sqrt{12,5.4,5}=7,5\left(cm\right)\)

Cũng có: \(BC^2=AB^2+AC^2\left(pi-ta-go\right)\\ \Rightarrow AC=\sqrt{\left(12,5\right)^2-\left(7,5\right)^2}=10\left(cm\right)\)

b) Xét \(\Delta ABH\) vuông tại H

Ta có: \(AB^2=BH^2+AH^2\left(PI-TA-GO\right)\Rightarrow AH=\sqrt{6^2-3^2}=\sqrt{27}\left(cm\right)\)

Xét \(\Delta ABC\) vuông tại A

Ta có: \(AH^2=BH.HC\left(HTL2\right)\Rightarrow HC=\dfrac{\left(\sqrt{27}\right)^2}{3}=9\left(cm\right)\)

Lại có: \(BC^2=AB^2+AC^2\left(pi-ta-go\right)\Rightarrow AC=\sqrt{\left(3+9\right)^2-6^2}=6\sqrt{3}\left(cm\right)\)

\(P\Delta ABC=AB+BC+AC=6+12+6\sqrt{3}=18+6\sqrt{3}\left(cm\right)\)

\(P\Delta ABH\) và \(P\Delta AHC\) bạn tự tính nha.

C_{M thu được} = \(\dfrac{0,3+0,2.1,5}{0,3+0,2}=1,2M\)

C% = \(\dfrac{1,2\times56}{10\times1,05}=6,4\%\)

n_{NaOH trong dd NaOH 1M}=0,3(mol)

n_{NaOH trong dd NaOH 1,5M}=0,3(mol)

C_M=\(\dfrac{0,3+0,3}{0,5}=1,2M\)

C%=\(\dfrac{40.1,2}{10.0,5}=9,6\%\)

n_NaOH = 10 : 40 = 0,25 mol

C_M NaOH = \(\frac{n}{V}=\frac{0,25}{0,25}=1\)M

xin hỏi? câu 3 bài 2 có thể chia là : The girl is smart whose eyes are bright không ạ

CHUYỂN THÀNH CÂU CÓ MỆNH ĐỀ QUAN HỆ:

EXERCISE 1:

1. The girl is sitting near Jack. She is the director.
……………The girl who is sitting near Jack is the director.……………………………………………………………….
2. Can you understand the question? The question is in page 14
………………………Can you understand the question which is in page 14
………………………………………1…………………………………………..
3. She is the woman? The woman met me last week.
……………………… She is the woman who met me last week.…………………………………………………
4. The farm produces eggs. The farm is beautiful
…………………………The farm which produces eggs is beautiful………………………………………………..
5. He married the girl. She loved him
…………………………He married the girl who loved him……………………………………………….
6. The man is an engineer. We talk to him every day.
……………The man to whom we talk everyday is an engineer……………………………………………………………….
7. He didn’t receive the letter. I sent him the letter last March.
………………He didn't receive the letter that i sent him the letter las march……………………………………………………………..
8. He often tells me something about his village. He was born there.
……………………He often tells me something about his village where he was born ……………………………………………………..
9. My sister wants to speak to you. You met my sister at my birthday party.
………………my sister, who y0u met at my birthday party , wants to speak to y0u. ……………………………………………………….
10. The children like the funny stories. They are from 5 to 10 years old.
……………………the children who are from 5 to 10 years old like the funny st0ries . …………………………………………………………………….
11. The boy will be punished. He threw that stone at me.
……………The boy who threw that stone will be punished.
……………………………………………………………
12. Thanh is the girl. I’m going to invite her to my birthday party.
………………thenh is the girl whom i am going to invite to my birthday party…………………………………………………………….
13. The man is a doctor. The doctor lives next to me
……………the man who lives next to me is a doctor…………………………………………………………….
14. The street is very narrow. The street leads to my school.
………………The streets that leads to my school is very narrow………………………………………………………….
15. It is the shop. My father works in the shop.
………………………It is the shop in which my father works…………………………………………………

EXERCISE 2:

1. The student is from China. He studies Vietnamese.

…………The students who studies vietnamese is from china…………………………………………………………
2. We are reading books. They contain English stories.

……………we are reading books which contain english stories……………………………………………………………..
3. The girl is smart. Her eyes are bright.

…………the girl whose eyes are bright is smart……………………………………………………………..
4. Saturday is the day. Boys and girls go together on that day ( when)

………………saturday is the day when boys and girls go together……………………………………………………..

5. Last year I visited a country. It is very beautiful.

…………Last year i visited a country which is veyr beautiful………………………………………………………
6. This is the village. She was born in it.

………………this is the village in which she was born………………………………………………….
7. I' ve sent him two letters. He has received them.

……………………He has received two letters which I've sent. ……………………………………………………
8. This is the phone .I like it very much.

…………….This is the phone which I like very much
………………………………………………………..
9 .This is the man .His son is my friend.

……………This is the man whose son is my friend.
…………………………………………………
10. Do you know the city? It is dirty

……………………Do you know the city which is dirty?…………………………………………
11. That is the house .I have lived in this house for 2 years .

………………That is the house where I have lived for 2 years.
………………………………………
12. The room looks beautiful .I painted it yesterday.

…………………The room that I painted yesterday looks beautiful .
………………………………………………..

13. Billy is a friend. I went on holiday with her.
-> ……………………

……………………..
14. This is Mr. Samson. His son Bill plays in our team.
->……………….This is Mr.Samson whose son Bill plays in our team.
………………………………
15. Her book was published last year. Her book became a best seller.
->…………………Her book that became a best seller last year was published ……………………………
16.This is the bank. We borrowed the money from it.
->……………this is the bank where we borrowed the money from……………………………….
17. I told you about a person. She is at the door.
->……………a person whom i told you is at the door………………………………….
18. I lent you a book. The book was written by one my friends.
->……………I lent you a book which was written by one of my friends…………………………………...
19. Some boys were ill. They have gone to hospital
->……………Some boys who have gone to hospital were ill………………………………….
20 Do you know a restaurant? We can have a good meal there.
->………Do you know a restaurant where we can have a good meal ?……………………………………….
21. I don’t remember the day. I left school on that day.
->…………I don't remember the day when i left school………………………………………..

22/ We threw out the computer. The computer never worked properly.

- ...................................We threw out the computer which never worked properly..............................................

Ta có :

\(\left(\frac{1}{2}\right)^{300}=\left(\frac{1}{8}\right)^{100}\)
\(\left(\frac{1}{3}\right)^{200}=\left(\frac{1}{9}\right)^{100}\)

Vì \(\frac{1}{8}>\frac{1}{9}\Rightarrow\left(\frac{1}{8}\right)^{100}>\left(\frac{1}{9}\right)^{100}\)

Hay \(\left(\frac{1}{2}\right)^{300}>\left(\frac{1}{3}\right)^{200}\)

Vậy..

b,Ta có:

\(\left(\frac{1}{3}\right)^{75}=\left(\frac{1}{27}\right)^{25}\)

\(\left(\frac{1}{5}\right)^{50}=\left(\frac{1}{25}\right)^{25}\)

Vì \(\frac{1}{25}>\frac{1}{27}\Rightarrow\left(\frac{1}{25}\right)^{25}>\left(\frac{1}{27}\right)^{25}\)

Hay \(\left(\frac{1}{3}\right)^{75}< \left(\frac{1}{5}\right)^{50}\)

Vậy..

- Để hai đường thẳng trên cắt nhau .

<=> \(m+1\ne3\)

<=> \(m\ne2\)

- Xét phương trình hoành độ giao điểm :

\(\left(m+1\right)x-1=3x-m\)

Mà hai đường thẳng cắt nhau tại điểm có hoành độ là -2 .

- Thay x = -2 vào phương trình trên ta được :

\(\left(m+1\right)\left(-2\right)-1=3\left(-2\right)-m\)

=> m = 3 ( TM )

Vậy ....

b) Ta có: \(\frac{8}{2^n}=2\)

\(\Leftrightarrow2^n=4\)

hay n=2

Vậy: n=2

c) Ta có: \(\frac{1}{2}^{2n-1}=\frac{1}{8}\)

\(\Leftrightarrow2n-1=3\)

\(\Leftrightarrow2n=4\)

hay n=2

Vậy: n=2