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9 tháng 2 2024

AC = \(\sqrt{BC^2-AB^2}\) = 12 (cm)

AD là trung tuyến, Ta có: \(AD^2=\dfrac{1}{2}\left(AB^2+AC^2\right)-\dfrac{BC^2}{4}\)

=> AD = \(\sqrt{\dfrac{1}{2}\left(AB^2+AC^2\right)-\dfrac{BC^2}{4}}\)

=> AD = 6.5

Tương tự với BE, CF ta đc:

BE = \(\sqrt{61}\)

CF = \(\dfrac{\sqrt{601}}{2}\)

Đây chắc ko phải bài lớp 7

9 tháng 2 2024

\(\dfrac{x^3}{8}=\dfrac{y^3}{64}\)

\(\dfrac{x^2}{8:x}=\dfrac{y^2}{64:y}=\dfrac{x^2+y^2}{8:x+64:y}=\dfrac{20}{8:x+64:y}\)

\(8:x+64:y\in\left\{-1;1;-2;2;-4;4;-5;5;-10;10;-20;20\right\}\)

Bạn kẻ bảng và xét từng trường hợp một, hoặc dùng phương pháp loại trừ để giảm số lượng thử trường hợp, khi đó ta tìm được.

\(\left\{{}\begin{matrix}x=-2\\y=-4\end{matrix}\right.or\left\{{}\begin{matrix}x=2\\y=4\end{matrix}\right.\)

9 tháng 2 2024

                 I.  Supply the correct tenses or forms in brackets (2pt ). 1.      She’d like ( buy ) some bananas.   ................................................................................................. 2.      I enjoy ( listen ) in my free time.     ................................................................................................. 3.      Lan ( be ) very tired when she  ( catch ) a bad cold two days ago.    ...
Đọc tiếp

                 I.  Supply the correct tenses or forms in brackets (2pt ).

1.      She’d like ( buy ) some bananas.

  .................................................................................................

2.      I enjoy ( listen ) in my free time.

    .................................................................................................

3.      Lan ( be ) very tired when she  ( catch ) a bad cold two days ago.

    .........................................................................................

4.      Everybody ( wait ) for the president in the hall now.

    .................................................................................................

5.      You should ( finish ) your homework before  watching  TV.

    .................................................................................................

6.      Lan ( be )fourteen years old  next week?

    .................................................................................................

7.      She never ( allow ) her children to stay up late.

    ...............................................................................................

             II.  Match the answers in column B to the questions in column A.

 

 

A

1.  Would you like to play chess?

2.  What is his height?

3.  What do you do in your free time ?

4.  What sport do you like best ?

                                  B

a.1,5 meters

b.I take part in outdoor activities with friends.

c.Badminton.

d.I’d like to but I can’t. I have to go now.

 

Read the passage carefully. Then do the exercises below. (2pts )

Well, I get up early. I always get up at 6.15 and I have a small breakfast. Then, my dad takes me to the swimming pool. I practice every day. I usually arrive at the pool at 7.20 and leave the pool at 8.20. After that, I go to school. Our lessons start at 9.10 and I don’t go home for lunch. I have my lunch at school.

We finish school at 3.45 and I go to the swimming pool again. I swim from 4.30 to 6.00. I usually have supper at 7.00, then I do my homework or watch TV. I sometimes write letters to my pen pals in Spain and Greece, but I always go to bed at 9.45. My friends go to bed at eleven o’clock or midnight! But I want to be a champion swimmer, so I go to bed early.

v True ( T) or False ( F ) (1pt)

1.  The writer’s school day lasts six hours and thrity – five minutes.

2.  The writer always writes letters to his pen pals in Spain and Greece.

v Answer the question. (1pt).

1.  What does the write do after supper ?

           

2.  How often does the writer go to the swimming pool?

           

1. Mr Robinson speaks Vietnamese very ________.
         A. fluent            B. fluently           C. influent            D. fluency

2. A lot of people love football. ________.
        A. So do I          B. So am I          C. Neither do I      D. Neither am I

3. Don't let the children play with knives. They are ________.
       A. danger           B. dangers          C. dangerous         D. dangerously

4. Nam isn't going to the movie theatre. Trung ________.
      A. isn't, too          B. isn't, either      C. isn't, neither      D. is, too

5. I like________ cartoons on television.
       A. watch             B. to watch         C. watched            D. watching

6. My mother cycles________.
       A. slowly            B. slow               C. lately                 D. usually

7. He was absent ________ school yesterday.
       A. at                  B. away              C. for                     D. from

8. He didn't do ________ yesterday.
       A. morning exercise                      B. morning exercises
       C. exercise morning                      D. exercises morning

II. Give the past form of these verbs (2pts)

1. get _________                5. speak ____________
2. play_________               6. see ____________
3. watch _________           7. invent ____________
4. finish _________            8. can ____________

III. Fill in the blanks with suitable prepositions (1 pt)

1. There aren't many good programs ______ teenagers.
2. What is _______ TV today?
3. You should eat plenty _______ fruit and vegetables.
4. They filled _______ their medical records.

IV. Use the correct verb forms (1pt)

1. I like (listen)_______to music.
2. He (get) ________ good marks at Math last week.
3. I must (clean)_______my room.
4. You ought (finish)________your homework before watching TV.

V. Make the questions for the answers (2pts)

1.__________________________________
He got up at six o'clock yesterday morning.
2. __________________________________
I brush my teeth three times a day.
3. ______________________________________
My mother went to bed early because she was tired.
4. ________________________________________
I am 40 kilos.

VI. Read the dialogue, then choose the best answer to complete the following sentences (2pts)

Trang: Would you like to come to my house for dinner?
Mai: Yes, I'd love to. What shall we do then?
Trang: We'll play some computer games. Do you like games?
Mai: Yes, sometimes. Why don't we see "Tom and Jerry" at 6.40 on VTV2?
Trang: Oh, my father doesn't love cartoon films. At this time he is watching a football match on VTV3. He prefers sports to other programs.
Mai: Oh, does your mother also like sport?
Trang: No, she doesn't. She likes films best. She likes all kinds of films, especially Vietnamese films.
Mai: How about you? Do you like films too?
Trang: No, I think films sometimes sound boring. Some films are too long, especially films of foreign countries. It takes me a lot of time to watch all of them.
Mai: Yes, I agree with you. I only prefer some programs for children. I guess we just like to do different things. Let's play chess after dinner.
Trang: Ok! It sounds interesting.

1. Trang invites Mai to come to ______ house for dinner.
          A. her                 B. my                 C. your

2. Trang wants Mai to _________ after dinner.
          A. see a football match                B. see cartoon films               C. play some games

3. Mai suggests they should _______ after dinner.
          A. play chess                              B. see a cartoon film               C. see a Vietnamese film

4. They can't watch TV after dinner because__________.
          A. Trang's family doesn't have a TV.
          B. they like to talk to each other.
          C. at that time her father is watching a football match.

5. Trang's father prefers ______ to other programs.
          A. Films           B. news                    C. sports

6. Trang's mother likes ______ the best. 
          A. films             B. news                   C. sports

7. Trang and Mai think films are ________ .
           A. boring          B. interesting           C. OK

8. At last, they ________ together.
           A. see some programs for children
           B. play games on computer
           C. play chess

 

I. Choose the word which has the underlined part pronounced differently from the others. (1mark)

1. A. Breakfast         B. Teacher            C. East              D. Please

2. A. Children           B. Church             C. Headache      D. Beach

3. A. See                 B. Salt                 C. Small             D. Sugar

4. A. Mother             B. Thirteen           C. Father            D. Then

II. Circle the word or phase (A , B , C or D) that best completes each of the following sentences. (2marks)

1. Phuong doesn’t like football and …… Mai .

   A. so is                 B. so does           C. does so          D. neither does

2. These papayas aren’t ripe and ….. are the pineapples .

   A. so                    B. too                  C. neither            D. either

3.The dirt from vegetables can make you …….. .

   A. bored               B. tired                C. sick                 D. well

4. You must do your homework more ……. in the future .

   A. careful             B. care                 C. careless          D. carefully

5. You should ……. early if you want to do morning exercise.

   A. get up             B. getting up          C. to get up         D. to getting up

6. Hoa is a ….. worker.

   A. hardly             B. hard                   C. more hard        D. most hard

7. Last night we didn’t watch the film on TV because it was ……..

   A. bore               B. bored                  C. boring             D. boredom

8 . Mai enjoys ….. sea food with her parents .

   A. to eat             B. eating                  C. eat                 D. to eating

III. Supply the correct forms of the verbs in brackets. (2marks )

1. He (wash)………………………….the dishes everyday.

2. We (play)…………………………volleyball tomorrow

3. She (not watch) …………………TV last night.

4. ……… they (go) …………………….to school now?

IV. Write the sentences. Use the cue words. (3marks )

1. I/not like/read books

…………………………………………………………………………………….

2. He/be/good/soccer/player.He/play/soccer/good.

…………………………………………………………………………………….

3. Mai/prefer/meat/fish.

…………………………………………………………………………………….

4 They/prefer/listen/music/watch/TV

…………………………………………………………………………………….

5 He/do/homework/last night.

…………………………………………………………………………………….

5 Hoa/not go/school/yesterday/because/she/be/sick.

…………………………………………………………………………………….

V. Read the passage carefully then answer questions. (2marks)

In 1960s, most people in Vietnam did not have a TV set. In the evening, the neighbors gathered around the TV. They watched until the TV programs finished. The children might play with their friends and the older people might talk together. Vietnam is different now. Many families have a TV set at home and the neighbors don’t spend much time together.

Questions:

1. Did most people have a TV set in 1960s?

2.How long did they watch TV programs?

3. What might the children do?

4. What might the older people do?

II. Supply the correct form of the verbs in brackets: (2.0 points)

1. My father (play)............... roller-skating when he was a child.

2. The disease (spread)....................... fast now.

3. I like (watch).................. basketball.

4. Marie Curie (receive)..............the Nobel Price for Chemistry in 1911.

5. Ba and Hoa would like (visit)............... Hong Kong.

6. We can (enjoy)................. traditional music.

7. Lan always (watch).................. TV in the evening.

8. Many years ago, most people in Vietnam (not have).............. TV sets.

III. Complete the sentences with in, before, after, on, at, till. (1.5 points)

1. Are you free.................. Monday?

2. We should wash our hands ............... meals.

3. Don't forget to brush your teeth.................... every meal.

4. The street is full of traffic from morning............. night.

5. I was born.................... 1976.

6. She's playing football......................... the moment.

1. - I don’t like jazz music. - _______________

A. I do either B. I am, too C. Neither do I D. So do I

2. Phong usually ________ TV in the evening, but yesterday evening he

________to music.

A. watches….. listens B. watches….. listened

C. watches….. is listening D. watched….. listens

3. How many people will take part ________the WTS day?

A. on B. for C. in D. at

4. My mother always drives ________ .

A. careful B. carefully C. slow D. fastest

5. You ought to ________ to the dentist.

A. going B. to go C. go D. will go

7
8 tháng 2 2024

           I.  Supply the correct tenses or forms in brackets (2pt ).

1.      She’d like ( buy ) some bananas.

  ..................to buy...............................................................................

2.      I enjoy ( listen ) in my free time.

    .................listening................................................................................

3.      Lan ( be ) very tired when she  ( catch ) a bad cold two days ago.

    ................was-caught.........................................................................

4.      Everybody ( wait ) for the president in the hall now.

    ....................is waiting.............................................................................

5.      You should ( finish ) your homework before  watching  TV.

    ...................finish..............................................................................

6.      Lan ( be )fourteen years old  next week?

    ....................Will-be.............................................................................

7.      She never ( allow ) her children to stay up late.

    ....................allows...........................................................................

             II.  Match the answers in column B to the questions in column A.

 

 

A

1.  Would you like to play chess?

2.  What is his height?

3.  What do you do in your free time ?

4.  What sport do you like best ?

                                  B

a.1,5 meters

b.I take part in outdoor activities with friends.

c.Badminton.

d.I’d like to but I can’t. I have to go now.

1 - d, 2 - a, 3 - b, 4 - c

8 tháng 2 2024

Read the passage carefully. Then do the exercises below. (2pts )

Well, I get up early. I always get up at 6.15 and I have a small breakfast. Then, my dad takes me to the swimming pool. I practice every day. I usually arrive at the pool at 7.20 and leave the pool at 8.20. After that, I go to school. Our lessons start at 9.10 and I don’t go home for lunch. I have my lunch at school.

We finish school at 3.45 and I go to the swimming pool again. I swim from 4.30 to 6.00. I usually have supper at 7.00, then I do my homework or watch TV. I sometimes write letters to my pen pals in Spain and Greece, but I always go to bed at 9.45. My friends go to bed at eleven o’clock or midnight! But I want to be a champion swimmer, so I go to bed early.

True ( T) or False ( F ) (1pt)

1.  The writer’s school day lasts six hours and thrity – five minutes.     T

2.  The writer always writes letters to his pen pals in Spain and Greece.     F

Answer the question. (1pt).

1.  What does the write do after supper ?

           The writer does his homework or watch T, and sometimes writes letter to pen pals

2.  How often does the writer go to the swimming pool?

           The writer goes to the swimming pool everyday

1. Mr Robinson speaks Vietnamese very ________.
         A. fluent            B. fluently           C. influent            D. fluency

2. A lot of people love football. ________.
        A. So do I          B. So am I          C. Neither do I      D. Neither am I

3. Don't let the children play with knives. They are ________.
       A. danger           B. dangers          C. dangerous         D. dangerously

4. Nam isn't going to the movie theatre. Trung ________.
      A. isn't, too          B. isn't, either      C. isn't, neither      D. is, too

5. I like________ cartoons on television.
       A. watch             B. to watch         C. watched            D. watching

6. My mother cycles________.
       A. slowly            B. slow               C. lately                 D. usually

7. He was absent ________ school yesterday.
       A. at                  B. away              C. for                     D. from

8. He didn't do ________ yesterday.
       A. morning exercise                      B. morning exercises
       C. exercise morning                      D. exercises morning

8 tháng 2 2024

Ta có \(\dfrac{a+b}{c}=\dfrac{b+c}{a}=\dfrac{a+c}{b}\)

Áp dụng tính chất của dãy tỉ số bằng nhau, thu được:

\(\dfrac{a+b}{c}=\dfrac{b+c}{a}=\dfrac{a+c}{b}=\dfrac{a+b+b+c+a+c}{c+a+b}\) \(=\dfrac{2\left(a+b+c\right)}{a+b+c}=2\)

\(\Rightarrow\left\{{}\begin{matrix}a+b=2c\\b+c=2a\\c+a=2b\end{matrix}\right.\)

Trừ theo vế 2 hệ thức đầu tiên, ta có

\(\left(a+b\right)-\left(b+c\right)=2c-2a\)

\(\Leftrightarrow a-c=2\left(c-a\right)\)

\(\Leftrightarrow3\left(c-a\right)=0\)

\(\Leftrightarrow c=a\)

Hoàn toàn tương tự, ta có \(a=b=c\)

Do đó \(\dfrac{a}{b}=\dfrac{b}{c}=\dfrac{c}{a}=1\)

Vậy \(P=\left(1+\dfrac{a}{b}\right)\left(1+\dfrac{b}{c}\right)\left(1+\dfrac{c}{a}\right)\)

\(=\left(1+1\right)\left(1+1\right)\left(1+1\right)\)

\(=8\)

8 tháng 2 2024

a) Có \(\dfrac{2x-y}{x+y}=\dfrac{2}{7}\) 

\(\Leftrightarrow7\left(2x-y\right)=2\left(x+y\right)\)

\(\Leftrightarrow14x-7y=2x+2y\)

\(\Leftrightarrow12x=9y\)

\(\Leftrightarrow\dfrac{x}{y}=\dfrac{9}{12}=\dfrac{3}{4}\)

b) Ta có \(\dfrac{t}{y}=\dfrac{4}{9}\) và \(\dfrac{z}{t}=\dfrac{5}{8}\)

\(\Rightarrow\dfrac{t}{y}.\dfrac{z}{t}=\dfrac{4}{9}.\dfrac{5}{8}\)

\(\Leftrightarrow\dfrac{z}{y}=\dfrac{5}{18}\)

\(\Leftrightarrow\dfrac{y}{z}=\dfrac{18}{5}\)

Lại có \(\dfrac{x}{y}=\dfrac{2}{3}\)

\(\Rightarrow\dfrac{x}{y}.\dfrac{y}{z}=\dfrac{2}{3}.\dfrac{18}{5}\)

\(\Leftrightarrow\dfrac{x}{z}=\dfrac{12}{5}\)

8 tháng 2 2024

 

 Trong tam giác ABC có \(\widehat{B}< \widehat{C}\) nên \(AC< AB\) (quan hệ giữa góc và cạnh đối diện trong tam giác)

 Hơn nữa, vì AH là đường cao của tam giác ABC nên BH, CH lần lượt là hình chiếu của AB, AC trên đường thẳng BC. 

 \(\Rightarrow CH< BH\) (quan hệ đường xiên - hình chiếu)

 (Bạn xem lại đề bài nhé, mình nghĩ nó là \(BH>HC\) đó. Nhìn từ hình vẽ cũng có thể thấy. Ý thứ 2 cũng vậy, mình nghĩ là \(BD>DC\))

8 tháng 2 2024

Mẫu số chung 2 phân số: 2929

\(\dfrac{18}{29}=\dfrac{18\cdot101}{29\cdot101}=\dfrac{1818}{2929}\)

\(\dfrac{70}{101}=\dfrac{70\cdot29}{101\cdot29}=\dfrac{2030}{2929}\)

Vì \(1818< 2030\) nên\(\dfrac{1818}{2929}< \dfrac{2030}{2929}\)

Vậy \(\dfrac{18}{29}< \dfrac{70}{101}\)

AH
Akai Haruma
Giáo viên
8 tháng 2 2024

Lời giải:

Do $a-b=13$ nên:

\(\frac{3a-b}{2a+13}-\frac{3b-a}{2b-13}=\frac{3a-(a-13)}{2a+13}-\frac{3b-(13+b)}{2b-13}\)

\(=\frac{2a+13}{2a+13}-\frac{2b-13}{2b-13}=1-1=0\)

8 tháng 2 2024

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