\(2x^2+x-3=0\)

Chiếu một chùm tia sáng song song trong không khí tới mặt nước (n=4/3) với góc tới là 45 độ. Góc hợp bởi tia khúc xạ và tia tới là?

Giải bất phương trình sau:
a.3(x+2)(x-2) ≤ \(3x^2+x\)
b.\(\dfrac{5x^2-3x}{5}+\dfrac{3x+1}{4}< \dfrac{x\left(2x+1\right)}{2}-\dfrac{3}{2}\)
c.\(\dfrac{x-15}{2002}+\dfrac{x-13}{2004}+\dfrac{x-11}{2006}\) ≤ 3

1.She finished the race although she was injured.    (Despite)
-> She finished the race.......................she was injured  (^^?)
2.Lisa's winter coat needs cleaning     (have)
->Lisa needs...................cleaned
3.Ben's mother insisted that he wash his hands before dinner.    (made)
->Ben................his hand before dinner by his mother
3.Somebody stole Paul's wallet when he was on holiday   (had)
-> Paul....................................when he was on holiday.

1.You must be acquainted........... all the facts before stating your opinion.
2.When did you last hear from him?    (since)
-> How long.............................heard from him?
3.He finds it difficult to address large audiences.    (difficulty)
-> He .......... large audiences
4.Would you mind moving over a little?    (kind)
-> would you be ..........over a little?

PHÁT ÂM /U/"
1.a.nurse      b.picture      c.surf      d.return
2.a.future      b.return       c.picture        d.culture
3.a.button     b.circus       c.suggest       d.future