1 +2 +3 + 4 + 5  + 6 + 7 + 8 + 9 + 10

=( 1+9 ) + ( 2 +8 ) + ( 3 + 7 ) + ( 4 + 6 ) + ( 5 + 10 )

=     10 +      10    + 10         +        10   +    15

= 55

1/8 nha bn

que kem

III. Make question from the underlined words

1. Where did you meet her last night?

We met her at the City's Theater last night.

2. How often does Nga brush her teeth?

Nga brushes her teeth three time a day.

3. When was your father in Hanoi?

My father was in Ha Noi three weeks ago.

4. Who does Nam play badminton with?

Nam plays badminton with Minh.

5. Why did she go to the doctor?

She went the doctor because she had a backache.

6. What are the students doing at the moment?

The students are practicing their English at the moment.

7. When was he have appointment?

He had appointment at 10.30.

8. How did they travel to the USA last month?

They traveled to the USA by plane last month.

71,20-49,69-5,20

=(71,20-5,20)-49,69

=66-49,69

=16,31

ai k mik mik k lại

good luck   ^.^

1. News programme starts at 7 p.m and finishes at 8 p.m.

-> News programme lasts for 1 hour.

Ta có P=(2n-1)/(n-1)=[2.(n-1)+1]/(n+1)=2.(n-1)/(n+1)+1/(n+1)=2+1/(n+1)

Vì 2 thuộc Z nên để P thuộc Z thì 1/(n+1) phải thuộc Z 

Nghĩa là n+1 thuộc Ư(1)={-1;1}

Do đó:

Vậy với n thuộc {-2;0} thì P thuộc Z

1. What subjacts do you have on Friday?

2. What are Phong and Nam doing at the moment?

3. How many floors at your new shool?

4. Who does Sam having lunch with?

5. What do you usually do after school?

6. How often does your brother go to the judo club?

7. When do we have Physics?

8. Where are they going?

18 h nha bạn

mình nhầm 

Số tiếp theo là 256 nha bạn