Xác định số oxi hóa của Nito trong các hợp chất sau: NH₃, N₂ ,NO, NO₂, HNO₃, NaNO₃
Ai giải giúp mik vs ạ

A=sin(30)+tan(64)-cos(60)-cot(26)

B=cos2(21)+cos2(13)+cos2(77)+cos2(69)

1. He (see) ... her while he (walk) ... down the street yesterday.

giải thích luôn với ạ

1. The __________ firefighter rushed into the burning building to save the trapped family.
2. She showed great __________ by offering to help her friend with their homework.
3. His __________ advice helped me make a difficult decision.
4. He was born into a __________ family.
5. The sunset over the ocean was so __________.
6. It's important to always tell the truth and practice __________, even when it's hard.
7. Listening to advice from someone with __________ can help you make good choices.
8. The teacher advised the students to be __________ while waiting for the test results.
9. She lifted the heavy box with ease, showing her __________.
10. The __________ lady helped the lost child find their way back home.
11. She didn't like the dress because she thought it was __________.
12. The __________ of the sunset took my breath away.
13. The athlete was very __________ and could lift heavy weights easily.
14. It is important to be __________ and tell the truth, even if it's hard.
15. Many people in the world live in __________
16. Despite the long wait, Sarah showed great __________ at the doctor's office.
17. She looked beyond his __________ and saw the kindness in his heart.
18. Despite feeling scared, she showed __________ and faced her fears.

cho $\tan \left(\alpha \right)=-4$.Tính
$Q=\frac{{\sin }^3\left(\alpha \right)-\cos \left(\alpha \right)}{2{\sin }^3\left(\alpha \right)-3{\cos }^3\left(\alpha \right)}$

33n+1-33n chia hết cho 32( với n là số tự nhiên)

n8 -n chia hết cho 6 với mọi n thuộc Z

Thu gọn đơn thức:
a/ 2x²y.3xy²
Chi mình hỏi câu này làm sao ạ

Mẫu thức chung của hai phân thức $\frac{\mathrm{x}}{\mathrm{xy}-{\mathrm{y}}^2}và\frac{y}{x^2-xy}là$

Xin chào, cô giáo giao cho nhóm mình đi thu thập đáp án cho các câu hỏi sau các bạn giúp nhóm mình trả lời câu hỏi bằng tiếng Anh nhé, cảm ơn các bạn ^^

1. When do you have free time?
2. What do you like doing with your family in your free time?
3. What do you like doing with your friends in your free time?
4. What leisure activities do you like doing on your own?
5. What leisure activities would you like to try in the future?

Câu 1 thực hiện phép tính a. $\frac{x^2-2}{x-1}-\frac{-1}{x-1}$

b, $\frac{x+3}{x^2-4}-\frac{1}{x^2-4}$  c, $\frac{x-2}{x-6}-\frac{18-x}{x-6}+\frac{x+2}{x-6}$

Câu 2 Áp dụng quy tắc đổi dấu để các phân thức có cùng mẫu thức rồi thực hiện phép tính. 

a, $\frac{2x^2-x}{x-1}+\frac{x+1}{1-x}--\frac{x^2-2}{x-1}$

b, $\frac{5}{y-1}-\frac{1}{1-y}+\frac{y}{y-1}$

c, $\frac{4-x^2}{x-5}+\frac{2x-x^2}{5-x}-\frac{4x-5}{x-5}$

câu 3 thực hiện phép tính 

a,a) 2+𝑎/2a - 1/2 

b,2/x-1 - 7-x/2x-2

c, 7/5-7x-31/5x-15

d,x^2+y^2 - 2(x^4+y^4)/x^2+y^2