Trong mp Oxy,3 điểm A(0,3),B(4,2),C(-1,-2)

a)tìm D sao cho \(\overrightarrow{AD}=\overrightarrow{AB}+3\overrightarrow{AC}\)

b)Tìm E thuộc Ox sao cho E,C,B thẳng hàng

Cho hbh ABCD,M là trung điểm cạnh CD,N là trung điểm đoạn BM.

CMR:\(\overrightarrow{AN}=\frac{3}{4}\overrightarrow{AB}+\frac{1}{2}\overrightarrow{AD}\)

Cho hcn ABCD có AB=4 CM,BC=2CM.Tính độ dài vecto \(\overrightarrow{CB}\) +\(\overrightarrow{DB}\)

Khi treo quả cân 300g vào đầu dưới của 1 lò xo(đầu trên cố định) thì lò xo dài 31cm.Khi treo thêm quả cân 200g nữa thì lò xo dài 33cm.Tính chiều dài tự nhiên và độ cứng của lò xo.(g=10m/s^2)

Một ô tô tải kéo 1 ô tô con có khối lượng 2 tấn và chạy nhanh dần đều với vận tốc ban đầu v0=0 ,sau 50s đi đc 40m.khi đó dây cáp nối 2 ô tô dãn ra bao nhiêu nếu độ cứng của nó là k=2,0.10^6 N/m?Bỏ các lực cản tác dụng lên ô tô con

Complete the sentences with the correct forms of the verbs:leave,change,know,come,reveal,finish,feed,share,refuse,return

1.Nothing can make Alex.........her mind now

2.Please let me.............your decision as soon as possible

3.it is customary......a gift from at least once or twice before finally accepting in japan

4.Hurry up!The train is about.................in five minutes

5.She did not know whether .......to her friend`s wedding or not

6.There are not enough candies......among all the children here

7.I saw my little sister.......the dog yesterday

8.I determine........all my homewrok today

9.You can use my car but you must promise............it before friday

10.My younger sister is not reliable enough.............my secret to her.

1.It began.........................(rain)when I was in London last saturday

2.We`ve decided.........(attend)the music contest at the end of this year

3.They intended.......(visit)Paris last year but they did not have enough time

4.Do not let him.....(know)about his mother is illness now

5.Someone saw him............(go)to a restaurant with his frienfs

6.This song makes everybody...............(feel)comfortabe

7.It is dangerous..........(go)out alone last at night

8.My father promised........................

1.The boys are playing games,...................the firls are waqtching tv

A.so B.nor C.and

2.I tried my best in the final test,.....the result was not as good as I expected

A.but B.so C.for

3.He lost the key,........he could not get into the house

A.yet B.or C.so

4.She loves comedies,...........her husband is interested in action films

A.for B.yet C.or

5.You must do well in the test,....you will not graduate

A.so B.or C.for

6.Pop music is so popular,.....the medoly is simple and memorable

A.for B.so C.and

7.I should pratice more for the competition,........my health has not been excellent recently

A.and B.so C.but

8.You can go to the movies with me ,.............you can go to the concert alone

A.and B.or C.so

1)My father allowed me (use)...............the camera

2)People use their money(buy).......and (sell)....things

3)She asked us (sit).....down and went (make).some coffee

4)Tim is too young(join)...the army

5)The movie was very sad.It made me (cry).....

6)Would you like(come).to dinner on Friday?

7)It took us three hours(get)..here

8)I`d rather (go).....(shop)........than anything else

9)I wonder if you`d be kind enough(help).....me

10)The robbers forced the manager(open).......the safe

1)We found it very difficult (reach/to reach)a decision

2)We are eager(to return/return)to school in the fall

3)I must (pay/to pay)the bill by tomorrow

4)She refused(to accept/accept)the gift

5)George pretended(to be/be)sick yesterday

6)They let her(go/to go)tonight

7)Carlos hopes(to finish/finish)his thesis this year

8)They agreed(to leave/leave)early

9)Helen was anxious(to tell/tell)her family about her promotion

10)He demands(to know/know)what is going on