a: A={1;2;3;4;5;6}; B={1;3;5;7;9}

=>C={2;4;6}

b: D={7;9}

c: E={1;3;5}

Ư(54)={1;-1;2;-2;3;-3;6;-6;9;-9;18;-18;27;-27;54;-54}

=>Các số vừa là bội của 3 vừa là ước của 54 là 3;-3;6;-6;9;-9;18;-18;27;-27;54;-54

Giải: 54 = 2.3³

Ư(54) = {-54; -27; - 18; - 9; - 6; -3; - 2; -1; 1; 2; 3; 6; 9; 18; 27; 54}

Những số vừa là ước của 54 vừa là bội của 3 là các số thuộc tập B trong đó:

B = {- 54; - 27; - 18; - 9; - 6; - 3; 3; 6; 9; 18; 27; 54} 

Liệt kê theo cặp các ước của 180.

Ư(180) = {1; 180; 2; 90; 3; 60; 4; 45; 5; 36; 6; 30; 9; 20; 10; 18; 15; 12}

P là tập hợp các ước không nguyên tố của 180. 

suy ra, P = {1; 180; 90; 60; 4; 45; 36; 6; 30; 9; 20; 10; 18; 15; 12}.

Vậy tập hợp P có 15 phần tử.

Vậy số phần tử của tập hợp P là: 15 phần tử

180 = 2².3².5

Số ước số của 180 là: (2 + 1).(2 + 1).(1 + 1) = 18 (ước)

Số ước số là số nguyên tố của 180 là 3 ước đó là các ước 2; 3; 5

Số ước số không phải là số nguyên tố của 180 là: 18 - 3 = 15 (ước)

Kết  luận P có 15 phần tử

Đề sai, em xem lại đề nhé

1. a. plays b. looks c. wants d. helps

2. a. books b. things c. programs d. rulers

3. a. serious b. symptom c. sauce d. sugar

4. a. horrible b. hour c. hundred d. hold

5. a. touched b. laughed c. talked d. rented

1a

2a

3d

4b

5d

Help 😭

1. I hope I ___________the exam.

a. will pass b. pass c. will passes d. am passing

2. He’s famous_____________ his invention.

a. of b. about c. for d. on

3. My father will _______________ me to the zoo tomorrow.

a. taking b. to take c. takes d. take

4. He enjoys_____________TV in his free time.

a. watching b. to watch c. watches d. wach

5. She goes swimming________________.

a. everyday b. everydays c. every day d. every Sundays

6. They ____________at home yesterday.

a. were b. was c. are d. is

7. We ______________ some flowers tomorrow.

a. will buy b. buy c. bought d. buying

8. Look! He _____________to music.

a. is listening b. listens c. are listening d. listen

9. _____________he eats breakfast, he will be hungry.

a. If b. Unless c. If not d. Because

10. If you don’t eat, you ____________hungry.

a. will b. are c. will be d. is

11. After supper, he went on_____________________ his homework.

a. do b. doing c. did d. does

12. I will tell him about it as soon as he_________________ back.

a. comes b. will come c. come d. to come

13. It was too late, so I had to go home_____________________ a hurry.

a. with b. on c. in d. for

14. He is working hard now, but he used to__________ very lazy.

a. was b. being c. is d. be

15. His father often makes him__________________ up early.

a. get b. to get c. gets d. getting

16. I like to travel _______________ a train.

a. on b. with c. through d. by

17. When you __________________ her, you will agree with me about it.

a. meet b. have meeting c. are meeting d. would meet

18. Look! Someone ______________________.

a. is coming b. are coming c. come d. coming

\(#FallenAngel\)

1. I hope I ___________the exam.

a. will pass b. pass c. will passes d. am passing

2. He’s famous_____________ his invention.

a. of b. about c. for d. on

3. My father will _______________ me to the zoo tomorrow.

a. taking b. to take c. takes d. take

4. He enjoys_____________TV in his free time.

a. watching b. to watch c. watches d. wach

5. She goes swimming________________.

a. everyday b. everydays c. every day d. every Sundays

6. They ____________at home yesterday.

a. were b. was c. are d. is

7. We ______________ some flowers tomorrow.

a. will buy b. buy c. bought d. buying

8. Look! He _____________to music.

a. is listening b. listens c. are listening d. listen

9. _____________he eats breakfast, he will be hungry.

a. If b. Unless c. If not d. Because

10. If you don’t eat, you ____________hungry.

a. will b. are c. will be d. is

11. After supper, he went on_____________________ his homework.

a. do b. doing c. did d. does

12. I will tell him about it as soon as he_________________ back.

a. comes b. will come c. come d. to come

13. It was too late, so I had to go home_____________________ a hurry.

a. with b. on c. in d. for

14. He is working hard now, but he used to__________ very lazy.

a. was b. being c. is d. be

15. His father often makes him__________________ up early.

a. get b. to get c. gets d. getting

16. I like to travel _______________ a train.

a. on b. with c. through d. by

17. When you __________________ her, you will agree with me about it.

a. meet b. have meeting c. are meeting d. would meet

18. Look! Someone ______________________.

a. is coming b. are coming c. come d. coming

1. I hope I ___________the exam.

a. will pass b. pass c. will passes d. am passing

2. He’s famous_____________ his invention.

a. of b. about c. for d. on

3. My father will _______________ me to the zoo tomorrow.

a. taking b. to take c. takes d. take

4. He enjoys_____________TV in his free time.

a. watching b. to watch c. watches d. wach

5. She goes swimming________________.

a. everyday b. everydays c. every day d. every Sundays

6. They ____________at home yesterday.

a. were b. was c. are d. is

7. We ______________ some flowers tomorrow.

a. will buy b. buy c. bought d. buying

8. Look! He _____________to music.

a. is listening b. listens c. are listening d. listen

9. _____________he eats breakfast, he will be hungry.

a. If b. Unless c. If not d. Because

1. I hope I ___________the exam.

a. will pass b. pass c. will passes d. am passing

2. He’s famous_____________ his invention.

a. of b. about c. for d. on

3. My father will _______________ me to the zoo tomorrow.

a. taking b. to take c. takes d. take

4. He enjoys_____________TV in his free time.

a. watching b. to watch c. watches d. wach

5. She goes swimming________________.

a. everyday b. everydays c. every day d. every Sundays

6. They ____________at home yesterday.

a. were b. was c. are d. is

7. We ______________ some flowers tomorrow.

a. will buy b. buy c. bought d. buying

8. Look! He _____________to music.

a. is listening b. listens c. are listening d. listen

9. _____________he eats breakfast, he will be hungry.

a. If b. Unless c. If not d. Because

10. If you don’t eat, you ____________hungry.

a. will b. are c. will be d. is

11. After supper, he went on_____________________ his homework.

a. do b. doing c. did d. does

12. I will tell him about it as soon as he_________________ back.

a. comes b. will come c. come d. to come

13. It was too late, so I had to go home_____________________ a hurry.

a. with b. on c. in d. for

14. He is working hard now, but he used to__________ very lazy.

a. was b. being c. is d. be

15. His father often makes him__________________ up early.

a. get b. to get c. gets d. getting

16. I like to travel _______________ a train.

a. on b. with c. through d. by

17. When you __________________ her, you will agree with me about it.

a. meet b. have meeting c. are meeting d. would meet

18. Look! Someone ______________________.

a. is coming b. are coming c. come d. coming

1. I hope I ___________the exam.

a. will pass b. pass c. will passes d. am passing

2. He’s famous_____________ his invention.

a. of b. about c. for d. on

3. My father will _______________ me to the zoo tomorrow.

a. taking b. to take c. takes d. take

4. He enjoys_____________TV in his free time.

a. watching b. to watch c. watches d. wach

5. She goes swimming________________.

a. everyday b. everydays c. every day d. every Sundays

6. They ____________at home yesterday.

a. were b. was c. are d. is

7. We ______________ some flowers tomorrow.

a. will buy b. buy c. bought d. buying

8. Look! He _____________to music.

a. is listening b. listens c. are listening d. listen

9. _____________he eats breakfast, he will be hungry.

a. If b. Unless c. If not d. Because

x+(x+1)+(x+2)+...+(x+10)=88

=>11x+(1+2+...+10)=88

=>11x+55=88

=>x+5=8

=>x=3

Bài 1:

\(\dfrac{x-2}{5}=\dfrac{-2}{2y+1}\)

=>\(\left(x-2\right)\left(2y+1\right)=5\cdot\left(-2\right)=-10\)

mà 2y+1 lẻ

nên \(\left(x-2;2y+1\right)\in\left\{\left(2;-5\right);\left(-2;5\right);\left(-10;1\right);\left(10;-1\right)\right\}\)

=>\(\left(x;y\right)\in\left\{\left(4;-3\right);\left(0;2\right);\left(-8;0\right);\left(12;-1\right)\right\}\)

Bài 2:

a: \(\left(2x-1\right)^2+4>=4\forall x\)

=>\(B=\dfrac{20}{\left(2x-1\right)^2+4}< =\dfrac{20}{4}=5\forall x\)

Dấu '=' xảy ra khi 2x-1=0

=>\(x=\dfrac{1}{2}\)

b: \(\left(x^2+1\right)^2>=1\forall x\)

=>\(\left(x^2+1\right)^2+5>=1+5=6\forall x\)

=>\(C=\dfrac{10}{\left(x^2+1\right)^2+5}< =\dfrac{10}{6}=\dfrac{5}{3}\forall x\)

Dấu '=' xảy ra khi x=0

BÀI 4A

\(\dfrac{1}{-2}+\dfrac{1}{-6}+\dfrac{1}{-12}+\dfrac{1}{-20}+\dfrac{1}{-30}+\dfrac{1}{-42}+\dfrac{1}{-56}+\dfrac{1}{-72}+\dfrac{1}{-90}\\ =-1\cdot\left(\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+\dfrac{1}{3\cdot4}+\dfrac{1}{4\cdot5}+\dfrac{1}{5\cdot6}+\dfrac{1}{6\cdot7}+\dfrac{1}{7\cdot8}+\dfrac{1}{8\cdot9}+\dfrac{1}{9\cdot10}\right)\\ =-1\cdot\left(\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{10}\right)\\ =-1\cdot\left(\dfrac{1}{1}-\dfrac{1}{10}\right)=-1\cdot\dfrac{9}{10}=-\dfrac{9}{10}\)