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Bài 1 :
\(S=\frac{2}{1.2.3}+\frac{2}{2.3.4}+...+\frac{2}{2009.2010.2011}\)
\(=\frac{1}{1.2}-\frac{1}{2.3}+\frac{1}{2.3}-\frac{1}{3.4}+...+\frac{1}{2009.2010}-\frac{1}{2010.2011}\)
\(=\frac{1}{1.2}-\frac{1}{2010.2011}<\frac{1}{2}\)
Vậy \(S<\frac{1}{2}\)
Bài 2:
Làm nhiều rồi vào trong chỗ góc học tập của tớ mà coi 
Ta có: 1/22< 1/1.2=1-1/2
1/32<1/2.3=1/2-1/3
..............................
1/1002< 1/99.100=1/99-1/100
Do đó: 1+1/22+1/32+...+1/1002< 1+1-1/2+1/2-1/3+....+1/99-1/100
=> 1+1/22+1/32+....+1/1002<1+1-1/100=2-1/100<2
nên 1+1/22+1/32+....+1/1002<2
Vậy 1+1/22+1/32+...+1/1002<2
Bài 1:
a)|x+1|-5=20-(-5)
\(\Leftrightarrow\)|x+1|=30
\(\Leftrightarrow\)\(\left[{}\begin{matrix}x+1=30\\x+1=-30\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=29\\x=-31\end{matrix}\right.\)
Vậy x=29 hoặc x=-31.
b)(-7)-|x+1|=32+(-11)
\(\Leftrightarrow\)|x+1|=28
\(\Leftrightarrow\left[{}\begin{matrix}x+1=28\\x+1=-28\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=27\\x=-29\end{matrix}\right.\)
Vậy x=27 hoặc x=-29.
tìm từ khắc với từ còn lại:
a) 1.fish 2.listen 3.time
b) 1.do 2. to 3. movies 4.go
c) 1.I 2. like 3.milk 4.die
d) 1. cold 2.close 3.hot 4.slow
e) 1.sea 2. tea 3 teather 4 weather
f) 1.chest 2.hand 3.head 4.toe 5.finger 6.big 7.noes
g) 1. table 2.chair 3 desk 4.couch 5.bench 6.hand
h)1.father 2.mother 3 sister 4.brother 5. people 6. uncle
i) 1. come 2. sit 3.desk 4.open 5. close 6. read 7.write 8. travel
a) 1.fish 2.listen 3.time
b) 1.do 2. to 3. movies 4.go
c) 1.I 2. like 3.milk 4.die
d) 1. cold 2.close 3.hot 4.slow
e) 1.sea 2. tea 3 teather 4 weather
f) 1.chest 2.hand 3.head 4.toe 5.finger 6.big 7.noes
g) 1. table 2.chair 3 desk 4.couch 5.bench 6.hand
h)1.father 2.mother 3 sister 4.brother 5. people 6. uncle
i) 1. come 2. sit 3.desk 4.open 5. close 6. read 7.write 8. travel
Good Effects
Television gives exposure to children on different cultural experiences.
Television also keeps children aware of current events and news related items.
Watching educational programs on television help the kids use it effectively, as a complement to school education.
Quality shows on television can impart knowledge and important values and lessons.
Watching music concerts and art shows can make the kids aware of the various genres of music around the world.
Television helps a child in spending time with family members, when all of them are watching the same show.
Watching documentaries, especially fragmented for children, opens doors of world in their mind.
Bad Effects
Excessive television viewing is seen to trigger violence or aggression in children.
Watching violent scenes at an early stage might make the kids scary of the world and find every other human being as mean. Often known as ‘mean and scary world’ syndrome, it might push them backwards in taking decisions of life.
Sitting in front of the television, for long hours, has been linked with obesity, as physical activity gets diminished considerably.
Children become influenced towards eating junk food, as there is a lot of promotion on the television, regarding the same.
The bombardment of sexual content on TV exposes teens to half-baked knowledge about sex at an early age, which is harmful for their mental growth. There is seldom mention of proper sex education or issues and risks related to it.
Devoting more time towards watching television leads to poor academic performance, as a child neglects his/ her studies.
Many advertisements and programs shown on television focus on beauty products and physical beauty, shifting kids’ interest from studies. They start paying more attention to their overall outlook. In extreme cases, they develop inferiority or superiority complex; leading to depression and underestimating themselves.
Television watching also promotes lack of creativity and enhances passivity. The child shies away from mental and physical workout.
The sense of relaxation that kids feel while watching television diminishes completely when it is switched off. This makes them watch TV for longer periods of time and makes them addicted to it
Television viewing creates the concept of gender-role and racial stereotypes in children, as they start considering it as very natural phenomena. Heroic acts are expected out of males, while women are displayed as objects and less powerful.
HƠI DÀI NHỈ~~~
\(c`3,4.0,7+3,4.0,3-0,4=3,4.\left(0,7+0,3\right)-0,4=3,4.10-0,4=34-0,4=33,6\)
\(d`\left(1-\dfrac{1}{2}+\dfrac{3}{4}\right)-\left(\dfrac{1}{2}+1\dfrac{3}{4}-3\right)=\left(1-\dfrac{1}{2}+\dfrac{3}{4}\right)-\left(\dfrac{1}{2}+\dfrac{7}{4}-3\right)=1-\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{1}{2}-\dfrac{7}{4}+3=\left(1+3\right)+\left(-\dfrac{1}{2}-\dfrac{1}{2}\right)+\left(\dfrac{3}{4}-\dfrac{7}{4}\right)=4+\left(-1\right)+\left(-1\right)=2\)
1. hair
2. course
3. country
4. photo
5. dance
6. paint
7. end
8. because
9. arm
10. cold
11. coy
12. climb
13. doctor
14. colour
15. summary
16. picture
17. eleven
18. watch
19. jeans
20. watch
21. begin
22. strong
2. course
3. country
4. photo .
5. dance
6. paint .
7. end
8. because
9. arm
10 . cold
12 . climb
13 . doctor
14 . colour
15 . summary
16 . picture
17 . eleven
18 . watch
19 . jeans
20 . watch
21 . begin
22 . strong