Cho 4,6g Na vào 100g dd NaOH 5% tính C% của dd NaOH PTHH 2Na + 2H2O ---> 2NaOH + H2

giúp mình bài 10 ạ !! thankk kiu

a) Nêu các công thức toán trong excel b)Nêu các hàm thường dùng trong excel c)Nêu các thao tác với bảng tính

a) (x-6)^2=9 b)|x|=3 c)|x+5|=15 d)4^2x-6=1 e)2^x-1=16 f) 5<5^x<125 g)5^x+1=125 h)5^2x-3=125

D=1/3^2-1/3^4-1/3^6-1/3^8+...+1/3^202-1/3^204

Bài 1: Buổi sáng Dương đi học lúc 6h40p và đến trường lúc 7h20p , mỗi h đi được 4,8km. Hỏi nhà bạn Dương cách trường bao nhiêu km? Bài 2: Lúc 7h sáng, Hoàng đi từ nhà mình lên huyện với vận tốc là 4km/h. Đến 10h An đi xe đạp đuổi theo với vận tốc 12km/h. Hỏi mấy giờ An đuổi kịp Hùng và chỗ đó cách nhau bao nhiêu km? Bài 3: Một tàu thủy xuôi dòng từ bến A đến bến B hết 10h và đi từ bến B về A hết 15h. Vận tốc ngược dòng kém vận tốc xuôi dòng là 8km/h. Hỏi: a,Tính vận tốc xuôi dòng/vận tốc ngược dòng? b,Khoảng cách từ bến A đến B?

Cho tam giác ABC vuông tại A biết AB=a vàB = 60 độ. Tính |−→AB +−→BC|; |−→AB −−→AC|

Tìm x a) (x - 3)^3 - (x - 3) (x^2 + 3x + 9) + 9(x + 1)^2 =15 b) x(x - 5) (x + 5) - (x - 2) (x^2 + 2x +4) = -17

Chứng minh : A =10^n + 8 / 3 là số tự nhiên ( m thuộc N )

Exercise 3: Rewrite the following sentences that keep the same meaning. 1. I don’t play tennis as well as you do. => You …………………………………………………….…………………………… 2. I haven’t been to the dentist’s for two years. => It’s …………………………………………………….…………………………….. 3. Whenever she went to Paris she bought a new dress. => She never …………………………………………………….……………………... 4. I spent seven years at secondary school and then I went to university. => After …………………………………………………….…………………………... 5. It’s not worth living to make her change her mind. => There’s …………………………………………………….………………………... 6. He said he was not guilty of stealing the car. => He denied …………………………………………………….……………………... 7. Is this the only way to reach the city centre? => Isn’t there …………………………………………………….…………………….? 8. He never suspected that the money had been stolen. => At no time …………………………………………………….…………………….. 9. It’s my opinion that you should take more exersise. => If I…………………………………………………….……………………………... 10. I was going to leave, but because of what he said, I didn’t. => She persuaded …………………………………………………….………………… Exercise 4: Rewrite the following sentences that keep the same meaning. 1. He was very sorry that he didn’t see Andrey on her trip to London. => He greatly regretted…………………………………………………………............. 2. It’s thought that the accident was caused by human error. => The accident is…………………………………………..…………………............... 3. “Will you be visiting the Taj Mahal when you go to India?” he asked Elizabeth. => He asked ……………………………………………………………………............. 4. “I think you should try the chicken Marengo,” said the waiter. => The waiter recommended ………………………………………………….. ............ 5. This is the most delicious cake I have ever tasted. => I have …………………………………………………………………………...…... Exercise 5: Rewrite the following sentences that keep the same meaning. 1. The questions are so easy that everyone can answer them. => They’re such ………………………………………………………………………... 2. The boy will receive some money to continue his study. His parents died in a traffic accident => The boy whose ………………………………....................................................…… 3. They are producing motorbikes in Vietnam. => Motorbikes are ……………………………………………………………………… 4. I wasn’t there yesterday, so I didn’t know who he was. => If I …………………………………………………………………………………... 5. If you do not try hard, you can’t pass the examination. => Unless ………………………………………………………………………………. 6. They spent more money, they had to work harder. => The more …………………………………………………………………………… 7. People thought that the cover was made of iron. => The cover …………………………………………………………………………… 8. He went to London. He had lived there when he was a boy. => He went to London where ………………………………………………………….. 9. Jane was absent from class because of her sickness. => Because Jane was …………………………………………………………………… 10. The package was too heavy for Peter to carry. => He package was so …………………………………………………………………..