30B 31B 32D 33D 34C 35B 36B 37C 38B 39A 40D 41D 42A 43D 44D 45A 46C 47B 48C 49B 50C 51C 52A 53D 54B 55C 56A 57C 58A 59D 60B

28.C

29.B

28.C

29.B

ko chắc ạ sai thông cảm

\(x^4-8x=x\left(x^3-8\right)=x\left(x-2\right)\left(x^2+2x+4\right)\)

\(x^2-y^2-6x+9=\left(x^2-6x+9\right)-y^2=\left(x-3\right)^2-y^2=\left(x+y-3\right)\left(x-y-3\right)\)

nhìu vậy mik trl một ít thui có đc ko

câu 6 : B cÂU 8 : c

6 b 7 d 8 mik ko bt 9 d 10 mik ko bt 11 d 12 b 13 d 14 d 15 b 16 b 17 b 18 b 19 a 20 b

1. Because he studies well, his parents are proud of him.

2. The salary was lơ but she accepted that job.

3. Learning English is very important.

4. She is keen on singing and dancing.

5. I prefer watching videos to reading books.

6. That car is not as expensive as this one.

7. Doing morninig exercise is very necessary.

8. Although he is poor, he helps the homeless people.

9. Living in the countryside is not as convenient as living in the city.

10. They enjoy going shopping.

11. It’s dangerous to go out late alone at night.

1 Because he studies well, his parent are proud of him

2 The salary was low by she accepted it

3 Learning English is very important

4 She is interested in singing and dancing

5 I prefer watching videos to reading books

6 That car is not as expensive as that one

7 Doing morning exercise is very necessary 

8 Although he is poor , he helps the homeless people

9 Living in the countryside is not as convenient than living in the city

10 They enjoy going shopping

11 It's dangerous to go out alone

\(n_{CuO}=\dfrac{8}{80}=0,1\left(mol\right)\\ PTHH:CuO+2HCl\rightarrow CuCl_2+H_2\uparrow\\ \left(mol\right).....0,1\rightarrow...0,2.......0,1......0,1\)

a) \(m_{CuCl_2}=0,1.135=13,5\left(g\right)\)

b) \(100ml=0,1l\)

\(C_{M_{CuCl_2}}=\dfrac{0,1}{0,1}=1\left(M\right)\)

Em cần hỗ trợ bài nào, em làm được bài nào rồi?

(1) S + O₂ ---t^o---> SO₂

(2) 2SO₂ + O₂ ---t^o---> 2SO₃.

(3) SO₃ + H₂O ---> H₂SO₄

(4) H₂SO₄ + BaCl ---> BaSO₄↓ + 2HCl

(5) SO₂ + Na₂O ---> Na₂SO₃.