Có nghiệm thì ∆ ≥ 0 nha bạn

Đk: 2x + 4 > 0 và 4 - 2x > 0

=> x > -2 và x < 2

=> TXĐ: D = (-2;2)

\(S=\dfrac{1}{2}\left(d_1.d_2\right)\)

\(\Leftrightarrow360=\dfrac{1}{2}\left(24.d_2\right)\)

\(\Leftrightarrow360=\dfrac{24d_2}{2}\)

\(\Leftrightarrow360=12d_2\)

\(\Leftrightarrow d_2=\dfrac{360}{12}\)

\(\Leftrightarrow d_2=30cm\)

I/

2. visited

3. am

4. will lend

5. would get

6. came

7. will see

8. gets

9. would tell

10. will wash

11. won't see

12. ate

13. have

14. got

15. will buy

II/

2. tell/will help

3. wouldn't marry/was

4. didn't fall/ wouldn't break

5. sings/will join

6. would go/were

7. was/would go

8. saw/would say

9. would go/ wasn't 

10. had/would give

11. played/would won

12. were/would accept

13. would have/didn't rain

14. went/would see

15. were/would help

16. knew/would go

18. doesn't lend/won't be

2. get lucky money

3. talent show

4. always

5. food stands

6. fireworks

7. never

8. eat traditional foods

1. on

2. at (be good at N/Ving: giỏi về cái gì đó)

3. in (be interested in N/Ving: cảm thấy thích về cái gì đó)

4. on

f. 

\(x+1>0\) và \(7-2x>0\)

\(\Leftrightarrow\left\{{}\begin{matrix}x>-1\\x< \dfrac{7}{2}\end{matrix}\right.\)

\(\Rightarrow\) TXĐ: \(D=(-1;\dfrac{7}{2})\)

g.

\(x+1>0\) và \(x^2-4\ne0\)

\(\Leftrightarrow\left\{{}\begin{matrix}x>-1\\x\ne2\\x\ne-2\end{matrix}\right.\)

\(\Rightarrow\) TXĐ: \(D=\left(-1;+\infty\right)\backslash2\)

1. did

2.watched

3. are

4. go

1. doing/is skipping

2. were

3. plays/is playing

4. do

5. saw

6. is/speaks/is going to come/is going to stay/is going to visit

7. swim

8. living

9. is

\(S=v_1.t_1=30.\dfrac{3}{2}=45km\)

\(\Rightarrow v_2=\dfrac{S}{t_2}=\dfrac{45}{1}=45\)km/h