\(\dfrac{4}{5}+\dfrac{3}{4}=\dfrac{16}{20}+\dfrac{15}{20}\\ =\dfrac{16+15}{20}=\dfrac{31}{20}\)

\(\dfrac{4}{5}+\dfrac{3}{4}\)

\(=\dfrac{16}{20}+\dfrac{15}{20}\)

\(=\dfrac{16+15}{20}\)

\(=\dfrac{31}{20}\)

a: Trên tia Ox, ta có: OA<OB

nên A nằm giữa O và B

=>OA+AB=OB

=>AB+4=6

=>AB=2(cm)

b: C là trung điểm của OA

=>\(CO=CA=\dfrac{OA}{2}=2\left(cm\right)\)

Vì AO và AB là hai tia đối nhau

nên AC và AB là hai tia đối nhau

=>A nằm giữa hai điểm B và C

Ta có: A nằm giữa B và C

mà AB=AC(=2cm)

nên A là trung điểm của BC

d: Các góc đỉnh D trong hình vẽ là: \(\widehat{ODC};\widehat{ODA};\widehat{ODB};\widehat{CDA};\widehat{CDB};\widehat{ADB}\)

b: \(cos14=sin76;cos37=sin53\)

Vì 47<48<53<76 nên \(sin47< sin48< sin53< sin76\)

=>\(sin47< sin48< cos37< cos14\)

c: \(cot25=tan65;cot38=tan52\)

Vì 52<62<65<73

nên \(tan52< tan62< tan65< tan73\)

=>\(cot38< tan63< cot25< tan73\)

a: Vì 75>45

nên \(tan75>1\)

Vì 40<45

nên \(cot40>1\)

\(cot40=tan50;tan75=tan75\)

mà \(tan50< tan75\)

nên \(1< cot40< tan75\left(1\right)\)

\(cos56=sin34;sin50=sin50\)

mà 34<50

nên \(sin34< sin50< 1\)

=>\(cos56< sin50< 1\left(2\right)\)

Từ (1),(2) suy ra \(cos56< sin50< cot40< tan75\)

A

glasses là cái kính, bao gồm 2 cái gắn vào khung, với lại từ glasses thì nó chỉ 1 cặp kính nghĩa là 2 cái

Bài 3:Điền dạng thích hợp của động từ trong ngoặc để hoàn thành các câu sau:

1.Did you enjoy(watch)__watching____the comedy last night?

2.Many people prefer(do)__doing____gardening after their retirement.

3.My cat dislikes(sleep)___sleeping_____on the floor.

4.My father doesn’t mind(work)____working__hard.

5.My cousin doesn’t like(study)___studying______Math and Chemistry.

6.They dislike(talk)_____talking_____with each other.

7.Jim and Jane don’t fancy(go)__going________out tomorrow.

8.Did you hate(eat)__eating____vegetables when you was small?

9.she didn’t prefer(tell)_____telling___him about her plan.

10.James'd like (have)___to have____dinner in a luxury restaurant.

11.I hope my mother will enjoy(spend)__spending_____time with her grandchildren.

12.Some people enjoy(take)___taking___a shower in the morning.

13.I think your brother won’t mind(lend)__lending______you a helping hand.

14.My boyfriend dislike(wait)_____waiting_______.

15.What do you detest(do)___doing_______the most?

Bài 4: Dựa vào các từ cho sẵn, viết thành câu hoàn chỉnh:

1.Peter/ enjoy / play/ computer games/ in his free time.

_____Peter enjoys playing computer games in his free time._________

2.You/ hate/ do/ the washing?

_____Do you hate doing the washing?____________________

3.My father/ enjoy/ play/ sports/ and/ read/ books.

_____My father enjoys playing sports and reading books. ___________

4.The teacher/ 'd like / help/ you/ with difficult exercises.

_____The teacher'd like to help you with difficult exercises.__________

5.Jane/ not fancy/ read/ science books.

______Jane does not fancy reading science books.__________________

6.Which kind of juice/ you/ dislike/ drink/ the most?

______Which kind of juice do you dislike drinking the most?__________________

7. Ann/ fancy/ do /DIY/ in her free time.

______Ann fancies doing DIY in her free time._________________

8. My father/ prefer/ not eat/ out.

________My father prefers not eating out._______________________

9.Mr.Smith/ love/ go/ shopping/ at weekend.

________Mr.Smith loves going shopping at weekend._____________________

10.Everyone/ adore/ receive/ presents/ on their birthday.

_________Everyone adores receiving presents on their birthday._____________

I.BÀI TẬP BỔ SUNG.

Exercise 1. Choose the correct answer.

1. Anna (likes/ hates) doing homework. She is lazy.

2. Lily (likes/ dislikes) the idea of staying out too late. It’s too dangerous.

3. Most girls (detest/ like) cockroaches.

4. Tom (likes/ hates) making models. He never does it.

5. We (enjoy/ hate) spending time with John. He is very interesting.

Exercise 2. Complete the sentences with the verb + -ing.

do; go; play; climb; swim; watch

1. Susan loves _____doing___________ yoga

2. They enjoy ______watching___________ the sports on TV.

3. We really like ____climbing_____________ in the Hoang Lien Son in February.

4. Simon hates _____playing____________ badmintons but he loves football.

5. I don’t like _______swimming____________ in the pool at the sports centre.

6. Do you like _______going_________ running in the morning?

Exercise 3. Rewrite the sentence without changing its meaning

1. My father likes to do gardening at the weekend.

→ My father enjoys _doing gardening at the weekend.__________.

2. She loves to collect glass bottles in her free time.

→ She enjoys _collecting glass bottles in her free time._____________.

3. I enjoy playing soccer.

→ I like playing soccer.____________________.

4. Do you like seeing a water puppet show?

→ Do you ____enjoy seeing a water puppet show?________________.

5. Do you enjoy making models with your friends?

→ Do you _____like making models with your friends?___________.

Exercise 4. Choose the best answer.

1. My mother loves _______ food for my family.

A. preparing      B. to prepare          C. prepare    D. A&B are correct.

2. My grandmother ________ to plant flowers in the garden behind her house.

A. 'd like        B. enjoys      C. detests      D. adores

3. Coco fancies ________ TV. He watches TV whenever he can.

A. to watch        B. watched       C. watch      D. watching

4. My sister hates  _______ with the dolls. It’s weird.

A. playing      B. to play     C. to playing      D. A&B are correct.

5. I enjoy ______ with my dog. He’s so cute

A. play             B. to play              C. playing        D. played

6. Tom fancies _______ computer games when he’s at home.

A. playing       B. to play                 C. played       D. A&B are correct.

7. Mary _______ reading Conan comics. She spends her free time on reading some volumes.

A. hates        B. detests         C. dislikes       D. enjoys

8. Henry doesn’t mind ________ up early in the morning.

A. waking        B. to wake       C. wake         D. will wake

9. My grandparents love ________ very much. There are a lot of beautiful flowers.

A. doing garden             B. doing gardening         C. do gardening      D. to do garden

10. Nga likes ________ with her close friend on Saturday evenings.

A. window shop       B. window to shop     C. window shops     D. window shopping

11. Do you fancy _______ around the West Lake with me this Sunday morning?

A going            B having            C. staying               D. moving

12. I don't like ________ up early in the winter days. I love ________ in bed late.

A. getting/ stay             B. get/ stay      C. getting/ staying      D. get/ staying

13. My father is fond of ________ a lot of trees and vegetables.

A. growing     B. grow       C. grew             D. grows

14. Teenagers often prefer travelling with their friends ________ travelling with their parents.

A. from        B. than      C. as         D. to

15. His parents are keen on  ________ to rock music at night.

A. listening     B. listen    C. to listen        D. to listening

Bài 3:Điền dạng thích hợp của động từ trong ngoặc để hoàn thành các câu sau:

1.Did you enjoy(watch)___watching___the comedy last night?

2.Many people prefer(do)___doing___gardening after their retirement.

3.My cat dislikes(sleep)_____sleeping___on the floor.

4.My father doesn’t mind(work)__working____hard.

5.My cousin doesn’t like(study)_____studying____Math and Chemistry.

3 D

4 A

5 A

6 D

7 B

Vì \(262\) chia cho số chia dư \(5\) nên \(262-15=247\) là số chia hết cho số chia

Ta có : \(247=13\times19=1\times247\)

Vì số chia là số tự nhiên có 2 chữ số nên số chia là \(13\) hoặc \(19\)

mà số dư là \(15\) nên số chia phải lớn hơn \(5\)

Suy ra số chia là \(19\)

Vậy số chia trong phép chia đó là \(19\)

Cho mình sửa chỗ " mà số dư là 15 nên số chia phải lớn hơn 15 " nhé !

`#3107.101107`

`a + b + c = 0`

`=> (a + b + c)^3 = 0`

`=> a^3 + b^3 + c^3 + 3a^2b + 3ab^2 + 3b^2c + 3bc^2 + 3a^2c + 3ac^2 + 6abc = 0`

`=> a^3 + b^3 + c^3 + 3a^2b + 3ab^2 + 3b^2c + 3bc^2 + 3a^2c + 3ac^2 + 6abc + 3abc - 3abc = 0`

`=> a^3 + b^3 + c^3 + (3a^2b + 3ab^2 + 3abc) + (3b^2c + 3bc^2 + 3abc) + (3a^2c + 3ac^2 + 3abc) - 3abc = 0`

`=> a^3 + b^3 + c^3 + 3ab(a + b + c) + 3bc(b + c + a) + 3ac(a + c + b) = 3abc`

`=> a^3 + b^3 + c^3 + (3ab + 3bc + 3ac)(a + b + c) = 3abc`

Mà `a + b + c = 0`

`=> a^3 + b^3 + c^3 = 3abc` (đpcm).

Phần tử là những đối tượng cụ thể được chứa trong tập hợp.

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