1B

\(x^{2n+25}:x^{n+22}=x^{2n+25-\left(n+22\right)}=x^{2n+25-n-22}=x^{n+3}\)

2A

3A

4D

\(9xy^2z\left(\dfrac{-1}{12}xy^2\right)2z=18xy^2z^2\left(\dfrac{-1}{12}xy^2\right)=\dfrac{-3}{2}x^2y^4z^2\)

5D

chưa biết đâu b à

1, \(MN\perp AB\) nên \(\widehat{AHE}=90^o\). \(\widehat{AKB}\) là góc nội tiếp chắn nửa đường tròn (O) nên \(\widehat{AKB}=90^o\Rightarrow\widehat{AKE}=90^o\). Tứ giác AHEK có \(\widehat{AHE}+\widehat{AKE}=90^o+90^o=180^o\) nên nội tiếp

2, \(\widehat{AKB}=90^o\Rightarrow AC\perp BK\Rightarrow BK//NF\) (vì \(NF\perp AC\))\(\Rightarrow\widehat{NKB}=\widehat{KNF}\left(slt\right)\), \(\widehat{MKB}=\widehat{KFN}\) (đồng vị) (1)

AB là đường kính vuông góc với dây MN tại H nên HM=HN. \(\Delta BMN\) có BH vừa là đường cao \(AB\perp MN\) vừa là trung tuyến (HM=HN) nên cân tại B => BM=BN\(\Rightarrow\stackrel\frown{BM}=\stackrel\frown{BN}\)

(O) có \(\widehat{MKB},\widehat{NKB}\) là 2 góc nội tiếp lần lượt chắn \(\stackrel\frown{BM},\stackrel\frown{BN}\), mà \(\stackrel\frown{BM}=\stackrel\frown{BN}\) nên \(\widehat{MKB}=\widehat{NKB}\) (2)

Từ (1), (2) \(\Rightarrow\widehat{KNF}=\widehat{KFN}\). Do đó \(\Delta NFK\) cân tại K

Mình chỉ giúp đc tới đây thôii

IV. Read these situations and write wishes you want to make for them

1. Your village does not have access to clean piped water.

    I wish …………your village had access to clean piped water………….

2. Your school is on the other side of a river, and you have to cross the river by boat twice a day to school.

    I wish ………your school wasn't on the other side of a river, and you didn't have to cross the river by boat twice a day to school…………….

    3. There is no organisation for social activities for teenagers in your town.

    I wish ………there was organisation for social activities for teenagers in your town……….

4. You are interested in basketball but you are not tall enough for the sport.

    I wish …………I was tall enough to play basketball…………….

5. In your area, there are only two seasons: dry and wet. You love autumn and spring.

    I wish …………there were four seasons in my area………….

6.I can’t visit my grandparents often.

   I wish …….…I could visit my grandparents often……….…

7.She won’t visit me again.

 I wish she would visit me again

8.My brother can’t speak English.

I wish …………my brother could speak English……………….

9.There are a lot of lessons and homework.

I wish ………there weren't a lot of lessons and homework….…….

10.I’m sorry that I can’t help you with this.

I wish…………I could help you with this….……….

11.I’m sorry that he isn’t with us now.

 I wish ………he was with us now……….……...

12.I regretted not telling him what happened last night.

I wish ………I had told him what happened last night……….

13.We live in a small flat.

We wish …………we didn't live in a small flat…………….

14.I was late for work this morning.

I wish …………I hadn't been late for work this morning………….

15.It’s a pity Minh will go to school tomorrow.

He …………wishes he wouldn't go to school tomorrow.……………

16.Thanh isn’t tall enough to play volleyball.

 She is too short to play volleyball

17.My little brother makes a lot of noise when he comes back from school.
I wish my little brother didn’t make a lot of noise when he comes back from school

18. He regretted borrowing his friend a bike.

He …………wishes he hadn't borrowed his friend a bike…………

19. I wished I hadn’t missed the train yesterday.

I regretted…………missing the train yesterday……………

20. She is sorry she is rude to me

She ………wishes she wasn't rude to me………………

Bài 4: Viết lại các câu sau sử dụng câu ước với “wish”.

1. I have to study hard.   

-> I wish I had studied hard

2. We had a lot of homework yesterday. 

-> I wish we hadn't had a lot of homework yesterday. 

3. It is raining heavily.

-> I wish ………it wasn't raining heavily……….

4. It was cold last night.

-> I wish ………it hadn't been cold last night….…….

5. They work slowly.  

-> I wish ………they didn't work slowly…………

5. She doesn’t join in the trip. 

-> I wish ………she joined in the trip…….……

6. I am not good at English.

-> I wish …………I was good at English.………

7. He studies badly. 

-> I wish ………he didn't study badly……….

8. He doesn’t like playing sports.

-> I wish ………he liked playing sports……….…

9. I don’t have a computer.   

-> I wish …………I had a computer……

10. Today isn’t a holiday.  

-> I wish ………today was a holiday.…………

11. I can’t sing this song.

-> I wish …………I could sing this song.…………

12. He was punished by his mother.

-> I wish ………he hadn't been punished by his mother…………

13. They won’t come here again.

-> I wish ………they would come here again………

14. He won’t go swimming with me.

-> I wish ………he would go swimming with me……….

15. We didn’t understand them.

-> We wish …………we had understood them…….…….

16. I will be late for school.

-> I wish ………I wouldn't be late for school….……….

17. The bus was late today.

-> I wish ………the bus hadn't been late today…….

18. She doesn’t like this place.

-> I wish …………she liked this place….………

19. These students talked too much in class.

-> I wish ………these students hadn't talked too much in class…………….

20. I can’t play basketball.

-> I wish/ If only …………I could play basketball……….……….

21. I regretted buying this old car

I wished………I hadn't bought this old car............

22. They could stay with me longer.

It’s a pity they………couldn't stay with me longer………

23. Lan wished she had told me about the truth

Lan regretted…………not telling me the truth…………….

I. Cho dạng đúng của từ

1. The....LEAVES.....of this tree are very green and beautiful. (LEAF)

2. Mr Pike lives on the...NINTH.....floor of this building. (NINE)

3.The coffee is too...HOT...for me to drink. (HEAT)

4. Who is the...RICHEST...person in the world? (RICH)

5. What is the....HIGHEST...mountain in the world? (HIGH)

6. He is a famous fottball.....PLAYER....(PLAY)

7. They are..TALKING...to their teacher (TALK).

8. Enghlish is an.....INTERESTING...and important subject. (INTEREST)

7D 

8. A

 \(N=6x^2-y^2-7xy-5x^2+2xy=x^2-y^2-5xy\)

2B 3A 4D 5B 6D