1. A. rough B. sum C. utter D. union 2. A. noon B. tool C. blood D. spoon 3. A. chemist B. chicken C. church D. century 4. A. thought B. tough C. taught D. bought 5. A. pleasure B. heat C. meat D. feed 6. A. chalk B. champagne C. machine D. ship 7. A. knit B. hide C. tide D. fly 8. A. put B. could C. push D. moon 9. A. how B. town C. power D. slow 10. A. talked B. naked C. asked D. liked Exercise 2 1. A. hear B. clear C. bear D. ear 2. A. heat B. great C. beat D. break 3. A. blood B. pool C. food D. tool 4. A. university B. unique C. unit D. undo 5. A. mouse B. could C. would D. put 6. A. faithful B. failure C. fairly D. fainted 7. A. course B. court C. pour D. courage 8. A. worked B. stopped C. forced D. wanted 9. A. new B. sew C. few D. nephew 10. A. sun B. sure C. success D. sort Exercise 3 1. A. month B. much C. come D. home 2. A. wood B. food C. look D. foot 3. A. post B. though C. how D. clothes 4. A. beard B. bird C. learn D. turn 5. A. false B. laugh C. glass D. after 6. A. camp B. lamp C. cupboard D. apart 7. A. genetics B. generate C. kennel D. gentle 8. A. cleanse B. please C. treat D. retreat 9. A. mechanic B. machinery C. chemist D. cholera 10. A. thank B. band C. complain D. insert 1. A. rough B. sum C. utter D. union 2. A. noon B. tool C. blood D. spoon 3. A. chemist B. chicken C. church D. century 4. A. thought B. tough C. taught D. bought 5. A. pleasure B. heat C. meat D. feed 6. A. chalk B. champagne C. machine D. ship 7. A. knit B. hide C. tide D. fly 8. A. put B. could C. push D. moon 9. A. how B. town C. power D. slow 10. A. talked B. naked C. asked D. liked Exercise 2 1. A. hear B. clear C. bear D. ear 2. A. heat B. great C. beat D. break 3. A. blood B. pool C. food D. tool 4. A. university B. unique C. unit D. undo 5. A. mouse B. could C. would D. put 6. A. faithful B. failure C. fairly D. fainted 7. A. course B. court C. pour D. courage 8. A. worked B. stopped C. forced D. wanted 9. A. new B. sew C. few D. nephew 10. A. sun B. sure C. success D. sort Exercise 3 1. A. month B. much C. come D. home 2. A. wood B. food C. look D. foot 3. A. post B. though C. how D. clothes 4. A. beard B. bird C. learn D. turn 5. A. false B. laugh C. glass D. after 6. A. camp B. lamp C. cupboard D. apart 7. A. genetics B. generate C. kennel D. gentle 8. A. cleanse B. please C. treat D. retreat 9. A. mechanic B. machinery C. chemist D. cholera 10. A. thank B. band C. complain D. insert

giúp em với ạ có đánh trọng ÂM đầy đủ 

Exercise 1 1. A. rough B. sum C. utter D. union 2. A. noon B. tool C. blood D. spoon 3. A. chemist B. chicken C. church D. century 4. A. thought B. tough C. taught D. bought 5. A. pleasure B. heat C. meat D. feed 6. A. chalk B. champagne C. machine D. ship 7. A. knit B. hide C. tide D. fly 8. A. put B. could C. push D. moon 9. A. how B. town C. power D. slow 10. A. talked B. naked C. asked D. liked Exercise 2 1. A. hear B. clear C. bear D. ear 2. A. heat B. great C. beat D. break 3. A. blood B. pool C. food D. tool 4. A. university B. unique C. unit D. undo 5. A. mouse B. could C. would D. put 6. A. faithful B. failure C. fairly D. fainted 7. A. course B. court C. pour D. courage 8. A. worked B. stopped C. forced D. wanted 9. A. new B. sew C. few D. nephew 10. A. sun B. sure C. success D. sort

Exercise1

1. A. rough B. sum C. utter D. union

2. A. noon B. tool C. blood D. spoon

3. A. chemist B. chicken C. church D. century

4. A. thought B. tough C. taught D. bought

5. A. pleasure B. heat C. meat D. feed

6. A. chalk B. champagne C. machine D. ship

7. A. knit B. hide C. tide D. fly

8. A. put B. could C. push D. moon

9. A. how B. town C. power D. slow

10. A. talked B. naked C. asked D. liked

Exercise 2

1. A. hear B. clear C. bear D. ear

2. A. heat B. great C. beat D. break

3. A. blood B. pool C. food D. tool

4. A. university B. unique C. unit D. undo

5. A. mouse B. could C. would D. put

6. A. faithful B. failure C. fairly D. fainted

7. A. course B. court C. pour D. courage

8. A. worked B. stopped C. forced D. wanted

9. A. new B. sew C. few D. nephew

10. A. sun B. sure C. success D. sort

Exercise 3

1. A. month B. much C. come D. home

2. A. wood B. food C. look D. foot

3. A. post B. though C. how D. clothes

4. A. beard B. bird C. learn D. turn

5. A. false B. laugh C. glass D. after

6. A. camp B. lamp C. cupboard D. apart

7. A. genetics B. generate C. kennel D. gentle

8. A. cleanse B. please C. treat D. retreat

9. A. mechanic B. machinery C. chemist D. cholera

10. A. thank B. band C. complain D. insert

Cần gấp !!!!!!!

Ai NHanh Mik TiCk

chọn từ có phần phát âm khác

1.A fan B phone C movie D laugh

2 A favour B rough C oven D view

3 A movement B fat C cofee D rough

4 A heavy B move C veal D stuff

5 A photo B fin C voice D feel

6 A veil B staff C vine D leave

7 A vast B fail C fine D sniff

8 A halve B half C vest D van

9 A half B feet C various D fill

10 A fun B visit C vote D vole

\frac{a}{1+b^{2}c}+\frac{b}{1+c^{2}d}+\frac{c}{1+d^{2}a}+\frac{d}{1+a^{2}b}\geq 2$

Ta có $\sum \frac{a}{1+b^2c}=\sum \frac{a^2}{a+ab^2c}$

Áp dụng Cauchy-Schwarzt ta có 

                 $\sum \frac{a}{1+b^2c}=\sum \frac{a^2}{a+ab^2c}\geq \frac{(a+b+c+d)^2}{a+b+c+d+ab^2c+bc^2d+cd^2a+da^2b}=\frac{16}{4+ab^2c+bc^2d+cd^2a+da^2b}$

Do đó ta chỉ cần chứng minh $ab^2c+bc^2d+cd^2a+da^2b\leq 4$ là suy ra $\sum \frac{a}{1+b^2c}\geq \frac{16}{4+4}=2$

Bất đẳng thức đã cho tương đương $ab.bc+bc.cd+cd.da+da.ab\leq 4$ với $a+b+c+d=4$

Chuyển $\left ( ab,bc,cd,da \right )\Rightarrow (x,y,z,t)$

Ta có $x+y+z+t=ab+bc+cd+ad \leq \frac{(a+b+c+d)^2}{4}=4$

Lại có $ab^2c+bc^2d+cd^2a+da^2b=xy+yz+zt+tx \leq \frac{(x+y+z+t)^2}{4} \leq \frac{4^2}{4}=4$

Vậy ta có đpcm

Dấu = xảy ra khi $a=b=c=d=1$

doc lam sao

I. Choose one letter (A, B, C or D) before the word that has the underlined part pronounced differently.

 1. A. tool      B. good       C. noon                D. school

 2. A. booked    B. looked   C.cooked        D. naked

 3. A. sound     B. favourite       C. cloud         D. found

 4. A. flowers   B. fields     C.parks         D. lemons     

5. A. pollution  B. collection  C. education D. suggestion