はい

World Wildlife Fund or Greenpeace, which are both working to help save whales.

Hãy chứng tỏ các tổng các ps sau > 1/2 A=1/12+1/13+1/14+1/15+...+1/22 B=1/10+1/11+1/12+1/13+...+1/99+1/100.Chứng tỏ rằ... - Olm

https://beta.olm.vn/cau-hoi/hay-chung-to-cac-tong-cac-ps-sau-12-a112113114115122-b1101111121131991100chung-to-rang-b1-c15161711.226046917923

a, Để B là phân số <=> 3n-3 khác 0 <=> 3n khác 3 <=> n khác 1

b, Để B nguyên thì 5n+2 chia hết cho 3n-3

<=> 15n+6 chia hết cho 3n-3

<=> 15n+6-5(3n-3) chia hết cho 3n-3

<=> 21 chia hết cho 3n-3

<=> 7 chia hết cho n-1

=> n-1 thuộc Ư(7) = {1;-1;7;-7}

=> n thuộc  {2;0;8;-6}

a, Để B là phân số <=> 3n-3 khác 0 <=> 3n khác 3 <=> n khác 1

b, Để B nguyên thì 5n+2 chia hết cho 3n-3

<=> 15n+6 chia hết cho 3n-3

<=> 15n+6-5(3n-3) chia hết cho 3n-3

<=> 21 chia hết cho 3n-3

<=> 7 chia hết cho n-1

=> n-1 thuộc Ư(7) = {1;-1;7;-7}

=> n thuộc  {2;0;8;-6}

a, Để B là phân số <=> 3n-3 khác 0 <=> 3n khác 3 <=> n khác 1

b, Để B nguyên thì 5n+2 chia hết cho 3n-3

<=> 15n+6 chia hết cho 3n-3

<=> 15n+6-5(3n-3) chia hết cho 3n-3

<=> 21 chia hết cho 3n-3

<=> 7 chia hết cho n-1

=> n-1 thuộc Ư(7) = {1;-1;7;-7}

=> n thuộc  {2;0;8;-6}

HT

  I=1

 V= 5

 X= 10

 D=500

 M=1000

tích cho mik nhá

  I = 1

 V = 5

 X = 10

 D = 500

 M = 1000

 HT

1. When do you often …………………the Independence Day? It’s on 2^nd, September.

A. celebrate                      B. enjoy                 C. have                  D. take

2. I really love autumn because it’s the time of the year when all the leaves …………..red or yellow.

A. have                            B. make                 C. increase             D. turn

3. There is a red maple………………on the flag of Canada, one of the English speaking countries.

A. bag                                        B. box                              C. leaf                              D. tree

4. This movie company………………..hundreds of famous films every year.

A. gives                           B. produces           C. does                  D. opens

5. This city is the biggest and the most …………….one in this country.

A. populated                    B. excited               C. invited               D. wanted

6. This year, the city welcomes more international…………………………coming to attend the Flower festival.

A. guests                          B. visitors              C. hosts                  D. partners

7. Do you know that the population of the city ……………….to over one million?

A. improves                     B. goes                  C. increases            D. stops

8. There are about 800 million English…………… in the word and this number is increasing day by day.

A. speakers                      B. cleaners             C. workers             D. actors

9. Australia is home to special ………………. kangaroos and koalas.

A. plants                          B. objects               D. people               D. animals

10.  I’ve heard that around one-fifth of the people in the ……………. are Chinese.

A. ocean                          B. planet                C. world                D. earth

1A 2D 3C 4B 5A 6B 7C 8A 9D 10C