rút gọn các biểu thức sau rồi tính giá trị biểu thức

1. Cho tứ giác ABCD, có hiệu của góc A và góc B là 400. Các tia phân giác của góc C và D cắt nhau tại H sao cho góc CHD có số đo là 1100. Chứng minh rằng AB vuông góc với BC.

2. Cho tứ giác ABCD có tổng của góc A và góc B là 2200. Các tia phân giác góc ngoài tại đỉnh C và D cắt nhau tại K. Tính số đo của góc CKD.

Exercise 2. Reorder the words to make correct sentences.
1. in / to / listening / time/ his / likes / pop / free / Dave / music/

2. to / the / is / son / addicted / My / Internet / using/.

3. mother / the / My / usually / news / reads / online/.

4. doesn’t / Jane / the / getting / like / early / in / up / morning/.

5. My / sometimes / brother / on / goes / with / fishing / friends / his / weekends/.

Exercise 3. Rewrite the following sentences based on the words in brackets.
1. I fancy making origami in my free time. (interested)

2. My brother dislikes going for a walk. (hates)

3. Are you a fan of romantic novels? (adore)

4. She detests snowboarding because it’s dangerous. (bad)

5. I’m obsessed with eating Korean food. (enjoy)

6. My sister and I fancy reading novels when we have free time. (fond)

7. Nowadays, many young people are addicted to surfing the Internet. (hooked)

8. Jenny dislikes doing karate, but she likes playing table tennis. (interested in - love)

9. We love watching movies at the cinema because of the great visual effects. (like)

10. My mother hates to commute to work by train because it is always crowded. (detest)
Exercise 4. Write complete sentences from the given cues. 
1. My son / crazy / play / computer / games.

2. The students / interested / play / football / after / school?

3. We / not / keen / make / models / because / we / not / patient / enough.

4. I / not / into / cook / because /1 / often / cut / myself.

5. My friends / fond / do / aerobics / and / they / go / gym / every / two / day.

6. John / like / play / computer games / free time.

7. My brother / enjoy / play / sports / and / read / books.

8. Julia / fancy / do / DIY / when / she / have / free time.

9. Everyone / adore / receive / gifts / their / birthday.

10. I/ prefer / hang / out / friends / play / board / games.

phân tích đa thức thành nhân tử

a,A=x³+y³+z³-3xyz

b,B=(x+y)³+(y-z)³+(z-x)³

c,C=(x²+x+1) (x²+x+2)-12

d,D=bc(b+c)+ac(c-a)-ab(a+b)

tìm x biết

a,-25+49x²=0

b,16x²-25(x-2)²

c,(3x-2)²-9(x+4)(x+4)=2

d,x³-6x²+12x-8=0

e,-27+27x-9x²+x³=0

giúp câu 5 đến câu 9 với