Một phân tử hợp chất A có 2 nguyên tố, nguyên tố X có 1 nguyên tử liên kết với 2 nguyên tử Cl và nặng hơn phân tử khí hidro 32 lần

a/ tính nguyên tử khối của X. Cho biết tên nguyên tố và kí hiệu

b/ tính phân tử khối của A (biết Cl=35,5, Cu=64)

Một phân tử hợp chất A gồm 2 nguyên tố, nguyên tố X có 1 nguyên tử liên kết với 4 nguyên tử H và nguyên tử X nặng hơn phân tử khí hidro 6 lần

a/ tính nguyên tử khối của X. Cho biết tên nguyên tố đó và kí hiệu

b/ tính phân tử khối của A (biết H=1,C=12)

viết dạng đúng của từ

1/ Nga (be) is Mai's friend. she (come) ... to Nha Trang last year. In Nha Trang Nga (live) ... with her aunt. The two girls (study) ... in the same class at Tran Phu school. Every day they (go) ... to school together. Nga (like) .... studying and playing with Mai. Now they (be) .... on their summer vacation. They (visit) .... Tri Nguyen aquarium next week.

2/ Trang (be) is Hoa's best friend. They (go) ... to the same class at Le Loi school. She (live) ..... with her parents in Da Lat. Yes she (receive) ... a letter from her grandparents. she (be) .... very happy. They (visit) .... her next sunday

3/ Nien (be) ... Hoa's next door neighbor in Hue. she (be) ..... very beautiful. She (have) .... big brown eyes and a lovely smile. Last week. she (go) ... to Ha Noi (visit) ... Hoa. Thay (travel) ... around the city and (see) .... a lot of interesting places. Nien (think) ..... Ha Noi (be). Beautiful but so noisy and busy, so she (not like) .... (like) ... there

hoàn thành câu với những từ đã cho

1. We/be/close friends/though/have/different character

2. Bao/always/get good marks/because/he/be/hard working

3. Song/spend/most/free time/play soccer

4. Weather/not/warm/us/go swimming

5. Bao's/volunteer work/not affect/school work

hoàn thành câu sau

1. Helen is my daughter .she is my (sister/nephew/cousin/niece)

2. Ba is sociable but his brother is quite (outgoing/shy/generous/kind)

3. A person who can neither speak nor hear is called (a deaf/a blind/a deaf-mute/a dumb)

4. His (sense of humor/quite character/kindness/annoyance) always makes people laugh

5. Nam often spends 1 hours a day (to study/study/studying/in studying) English

6. Would you like to go to the movie with me tonight? (yes, please/i'm sorry/i'd love to/no thanks/yes, i'd love to )

7. Can i speak to Marry, please? - please (stay there a minute/hold on/keep the phone/wait the phone)

8. The earth, the sun,the mars, the moon are (object/planets/friends/things)

9. Is dane in ? no, he's out. would you like to leave a (message/letter/telephone/call)

10. Alexandar Graham Bell was born .... Edinburgh .... march 3,1847 (of-in/in-of/in-on/at-on)

11. He worked ... deaf mute patients .... a hospital in Boston (for-in/for-at/with-for/with-in)

12. I'm sorry, but you'll have to cook dinner (myself/yourself/himself/herself)

13. You have to put all dangerous objects ... children's reach (out of/far away/next to/inside)

14. Mr.vinh is bald because he has no (eyes/head/ears/hair)

15. I spend most of time .... my friends (with/at/together/for)

16. You can use a .... to receive message when you are out (public phone/telephone directory/answering machine/mobile phone)

17. I want to talk to Tomy in England. I'm going to a call (make/do/take/bring)

18. I want to talk to the doctor. Could you .... a metting (arrange/make/tell/call)

19. He was a Scotsman although he later .... canada (emigrated/moved/lived/went)

20. Could you ... a message? i want to leave your mum a message (give/take/need/want)

chứng minh rằng

n⁴-4n³-4n²+16n chia hết cho 384

chứng minh rằng

a/ 3n⁴ -14n³+21n²-10n \(⋮\) 24 với n \(\in\)Z3

b/ n⁵-5n³+4n \(⋮\) 120 với n \(\in\) Z

c/ n³-5n²-n+3 \(⋮\)48 với n \(\in\)Z

hãy so sánh sự giống và khác nhau giữa cách mạng tư sản pháp và mĩ

tính

x³+ax²-4\(⋮\)x²+4x+4

tính

ax⁵+5x⁴-9\(⋮\)x-1