Bài 24: Chứng minh các đa thức sau luôn dương với mọi x,y

a) x²+ 2x +2

b) 4x² - 12x +11

c) x² - x +1

Bài 22: Tính giá trị biểu thức

c) C = x³ - 9x² + 27x - 26 với x = 23

d) D = (2x-3)² - (4x-6)(2x-5) + (2x-5)² với x = 99

Bài 19: Biến đổi các biểu thức sau thành tích các đa thức:

a. x³+8

b. 27-8y³

c. y⁶ +1

d. 64x³ - \(\dfrac{1}{8}\)y³

e. 125x⁶ - 27y⁹

f, -\(\dfrac{x^6}{125}\) - \(\dfrac{y^3}{64}\)

Sử dụng 7 hằng đẳng thức ở lớp 8 để tính:

a. (2x-3) (4x² + 6x +9) - (2x+3) (4x² - 6x +9)

b. (x+1) (x² - x +1) - (x-1) (x² +x +1)

c. (3x-1) (3x+1) - (3x-2)²

d. (2x - 3)² - (2x +3) (2x-3)

e. (3x-4)² - (2x+4)²

f. (3x - 5)³ - (3x+5)³

g. (2x-1)² - (3x-1)²

h. (x-2y) (x² +2xy + 4y²) + (x³ - 6y³)

Reorder to make a complete sentence.

1. enough / Jane / stay / to / alone / old / isn't / at home.

2. you / going / to / are / what / do / next weekend?

3. she / hair / black / has / long / straight.

4. in the east / rises / sun / the / in the west / sets / and.

5. table / large / was / in the kitchen / there / a / wooden / round.

6. awful / an / what / house!

7. have / money / buy / that / we / enough / to / didn't / car.

8. free / he / most / time / sport / spends / of / his / playing.

Use the correct preposition

1. There are usually a lot of parties........................Christmas.

2. I received a letter...................my Australian pen pal Mindy yesterday.

3. She usually goes swimming .......................Friday afternoon.

4. Khoi is my close friend. I spend most of my time ................him.

5. Are you tired......................listening to her complaints?

6. His friends don't laugh....................his joke.

7. My Dad is loved because of his good sense ....................humor.

8. He lives..................26 Tran Phu Street ..................Ha Noi.

9. His idea is quiet different ........................mine.

10. What does she look..............?

1)Tìm x biết:

a. 4x . (2x² - 1) + 27 = (4x² + 6x + 9) . (2x + 2)

b. (2x + 1) . (5x - 1) = 20x² - 16x - 1

Find the opposite word.

a. dark ......................

b. ugly ......................

c. outgoing ......................

d. lively ......................

e. long ......................

f. quiet ......................

g. straight ......................

h. weak ......................

i. boring ......................

k. unfriendlly ......................

l. generous ......................

Put the words correct order to make complete sentences.

1. brown / has / eyes / she / big.

2. gray / a / Mr. Thanh / beard / long / has.

3. many / are / flowers / garden / in / red / her / there / small.

4. car / is / black / it / big / a.

5.talking / man / is / a / she / handsome / to / tall.

6. sister / short / does / hair / Linh's / wasvy / have?

7. married / fat / she / short / a / man / to.

8. teacher / dark / has / our / hair / straight / long.

9. daughter / blond / has / hair / his / long.

1. Jet enginess (make)..................a lot of noise.

2. The sea (cover).............. two third of the world.

3. Loud music (give).................... me a headache.

4. We (go)....................... to school from Monday to Saturday.

5. She usually (finish)................. her work at 5:30.

6. He (play)................ the guitar and the piano.

7. It (slow).......................a lot during the winter in his country.

8. The River Amazon (flow).......................into the Atlantic Ocean.

9. Vegetarians (not eat).......................meat or fish.

10. Oranges (be)................rich in vitamin C.

11. I (be).......................at school at the weekend.

12. She (not study)...................... on Friday.

13. My student (be not).............................. hard working.

14. I usually (have).............................breakfast at 7:00.

15. .....................she (live)........................in a house?

16. Where (be)....................................your children?

17. My sister (work)...................................in a bank.

18. Dogs (like).........................meat.

19. It (rain)...........................almost every summer.

20. My mother (fry)...........................eggs for dinner every evening.

21. The bank (close)..........................at 4;00.

22. John (try)...................hard in class, but I (not think)............................... he'll pass.

23. My life (be)..........................so boring, I just (watch).........................TV everynight