Giúp mình vs tối nay mình phải nộp rồi😭😭😭, mình cám ơn trước nha!!!
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Câu 1:
1: \(\overrightarrow{OM}=\dfrac{\overrightarrow{OA}+\overrightarrow{OD}}{2}=\dfrac{\overrightarrow{BO}+\overrightarrow{OA}}{2}=\dfrac{\overrightarrow{BA}}{2}=-\dfrac{1}{2}\overrightarrow{AB}\)
\(\Leftrightarrow x=-\dfrac{1}{2}\)
\(\overrightarrow{BD}=2\cdot\overrightarrow{BO}=-2\cdot\overrightarrow{OB}\)
nên y=-2
2: \(2\cdot\overrightarrow{ON}=\overrightarrow{OB}+\overrightarrow{OC}=\overrightarrow{DO}+\overrightarrow{OC}=\overrightarrow{DC}=\overrightarrow{AB}\)
Vậy: Các vecto u thỏa mãn là vecto DC và vecto AB
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{-6}{30}=\frac{x}{-20}\)
nhân chéo \(x\cdot30=\left(-6\right)\cdot\left(-20\right)\)
=>\(30x=120\)
\(x=4\)
\(\frac{-6}{30}=\frac{3}{y}\)
nhân chéo => \(-6x=90\)
\(x=-15\)
\(\frac{-6}{30}=\frac{z}{5}\)
nhân chéo => \(30z=-30\)
\(z=-1\)
x/-20 = -6/30
=> 30x = 120
<=> x = 4
3/y = -6/30
=> -6y = 90
<=> y = -15
z/5 = -6/30
=> -6z = 150
<=> z = - 25
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
d: ta có: \(C=3+3^3+3^5+...+3^{1991}\)
\(=3\left(1+3^2+3^4\right)+...+3^{1987}\left(1+3^2+3^4\right)\)
\(=91\cdot\left(3+...+3^{1987}\right)⋮13\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài làm:
Số lẻ bé nhất có ba chữ số là : 101
Tổng của hai số là :
101 x 2 = 202 ( đơn vị )
Số cần tìm là :
202 - 96 = 106 ( đơn vị )
Đ/s : 106 đơn vị
![](https://rs.olm.vn/images/avt/0.png?1311)
I
1 works - will pass
2 had - would buy
3 come - will phone
4 will feel - don't give
5 closed
6 goes - will be
7 will know - don't reveal
8 have
9 won
10 will stop
II
1 if I wanted to dance
2 when I had come
3 if John had arrived
4 where Maria parked her car
5 If I had watched the latest film
6 if she could help me
7 they had cleaned the windows
8 he hadn't had time to do his homework
9 her mother would be 50 years old
10 the boss had to sign the letter
Phần trên mình làm ở câu hỏi trước của bạn rồi nhớ.
III.
1. doesn't never drink -> never drinks
2. dressing -> dressed
3. Yes -> No
4. are -> will
5. nine -> ninth
6. Who -> How
7. tooth -> teeth
8. many -> much
9. do -> does
10. at -> in
V.
1. worse
2. as good as
3. wider
4. bigger
5. harder
6. tougher
7. fewer
8. narrower
9. the fastest
10. happier
D.
I.
1. A
2. B
3. D
4. D
5. B
II.
1. It is 3 years since we last went to Spain.
2. We have arrived in Budapest for 2 days.
3. This is the second time I have visited the Stone Forest.
4. Dung is keen on travelling.
5. If you don't turn off all the lights, you will pay more money.
Câu 1:
1: \(\overrightarrow{OM}=\dfrac{\overrightarrow{OA}+\overrightarrow{OD}}{2}=\dfrac{\overrightarrow{BO}+\overrightarrow{OA}}{2}=\dfrac{\overrightarrow{BA}}{2}=-\dfrac{1}{2}\overrightarrow{AB}\)
\(\Leftrightarrow x=-\dfrac{1}{2}\)
\(\overrightarrow{BD}=2\cdot\overrightarrow{BO}=-2\cdot\overrightarrow{OB}\)
nên y=-2
2: \(2\cdot\overrightarrow{ON}=\overrightarrow{OB}+\overrightarrow{OC}=\overrightarrow{DO}+\overrightarrow{OC}=\overrightarrow{DC}=\overrightarrow{AB}\)
Vậy: Các vecto u thỏa mãn là vecto DC và vecto AB