1 Sue wishes she hadn't bought that new book

2 Unless you walk faster, you will be late

3 Carol spent 2 hours fixing the television sets

4 I make these handicrafts by myself 

5 If I were you, I would take the bus instead of the train

II

1 She doesn't have to get up early on Saturday

2 Children mustn't be left alone in car

3 John must explain this if he want his student to succeed

4 I have to file the report this week

5 We don't have to work overtime on Saturdays

6 You mustn't drive more than 25 mph in this zone

7 She didn't have to attend the presentation yesterday

8 She has to pick up her children at school

9 You don't have to arrive before 8

10 They had to visit the doctor yesterday as they didn't feel well

a) điện trở tương đương của đoạn mạch

R_tđ = R1 + R2 =10 + 20= 30 (Ω)

Cường độ dòng điện chạy qua đoạn mạch

I = \(\dfrac{U}{Rtđ}=\dfrac{6}{30}=0,2\left(A\right)\)

b) vì R1 nối tiếp R2  nên ta có:

I= I1= I2 = I3= 0,2 (A)

-> U1= I1 . R1 = 0,2 .10 = 2 (V)

-> U2 = I2 . R2 = 0,2. 20 = 4 (V)

pollution

amazing

why didn't hoa go to school yesterday - Because she had a bad cold

What kind of movies do you enjoy - mostly comedies

How many people atted .... - more than 6 million

are people's lives.... - Yes of course

Do you think ... - I think population...

22.pollution

23.amazed

24. 

1 vàng với 2 xanh

2 vàng với 1 xanh

3 vàng với 5 xanh

4 vàng với 4 xanh

5  vàng với 3 xanh

tui kh bic cậu còn cần kh nhma đây nhéeeee

22/ \(\omega A=8\pi\)

\(A^2=x^2+\dfrac{v^2}{\omega^2}\Leftrightarrow A^2=3,2^2+\dfrac{\left(4,8\pi\right)^2}{\omega^2}\)

\(\Leftrightarrow\omega^2A^2=3,2^2\omega^2+23,04\pi^2\Leftrightarrow64\pi^2=3,2^2.\omega^2+23,04\pi^2\Leftrightarrow\omega=2\pi\left(rad/s\right)\)

\(\Rightarrow f=\dfrac{\omega}{2\pi}=\dfrac{2\pi}{2\pi}=1\left(Hz\right)\Rightarrow D.1Hz\)

23/ \(\omega A=20;\omega^2A=80\Rightarrow\left\{{}\begin{matrix}\omega=4\left(rad/s\right)\\A=5cm\end{matrix}\right.\)

\(\Rightarrow v=\omega\sqrt{A^2-x^2}=4.\sqrt{5^2-4^2}=12\left(cm/s\right)\Rightarrow A.12cm/s\)

1 C

2 B

3 A

4 B

5 C

hic cíu mng oi

a: ĐKXĐ: \(x\notin\left\{10;-10;\sqrt{10};-\sqrt{10}\right\}\)

b: \(A=\dfrac{5x^3+50x+2x^2+20+5x^3-50x-2x^2+20}{\left(x^2-10\right)\left(x^2+10\right)}\cdot\dfrac{x^2-100}{x^2+4}\)

\(=\dfrac{10x^3+40}{\left(x^2-10\right)\left(x^2+10\right)}\cdot\dfrac{x^2-100}{x^2+4}\)