Tính nồng độ các ion trong dd thu được khi:

a) Trộn 200ml dd NaCl 2M với 200ml dd CaCl₂ 0,5M

b) Trộn 200ml dd chứa 12g MgSO₄ với 300ml dd chứa 34,2 gam Al₂(SO₄)₃

giải pt: sin2x - cos3x = 0

giải pt: cot ( 4x/5 - 45 độ)  = -1/2

1. He ought to stop wasting money on lottery

2. You must finish your homework before going to bed

3. You do not have to bring food and drink for lunch 

4. You mustn’t fish in this park 

5. Every receptionist in our hotel have to wear a uniform

6. Shops mustn’t sell cigarettes to children

7. Waiters do have to wear a tie

8. He ought not to drink too much alcohol 

9. Every employee has to  keep the company's information secret

10. I ought to study English to get a good job

giải pt: cot ( 2x - 3 ) = 1/4

giải pt: sin ( 2x + 35 độ) = -√2/3

Giải pt: sin ( 3x/4 - π/6 ) = 0

giải pt: sin (x + 3) = 2/3

giải pt: cosx = 1/2