thiếu dữ liệu hay s ý?

\(x^2\) + 357 = y² ⇒ y² > 357 mà y là số nguyên tố nên \(y\) là số lẻ

⇒ y² là số lẻ. ⇒ y² - 357 là số chẵn mà \(x^2\) = y²  - 357

⇒ \(x^2\) là số chẵn; \(x\) \(\in\) P ⇒ \(x\) = 2

Thay \(x\) = 2 vào biểu thức \(x^2\) + 357  = y² ta có:

                                          2² + 357  = y²

                                          y²           = 361

                                           y           = \(\pm\) 19

Vì y là số nguyên tố nên y = 19

Kết luận hai số nguyên tố \(x\); y thỏa mãn đề bài là: 

(\(x\); y) = (2; 19)

1.D

2.B

3.A

4.D

5.B

6.D

7.C

8.A

9.B

10.D

11.B

12.B

13.A

14.B

15.A

16.C

17.A

18.B

19.D

20.B

1.  The Great Wall of China is the world’s longer => longest structure.

       A                      B                 C                 D

2.  Traveling by tram is most => more convenient than traveling by car in this city.

                               A          B                       C                     D

3.  You must taking=> take off your shoes before entering this room.

                              A           B                C                  D

4.  Do you think there is another mountain highest => higher than Mount Everest?

      A                      B              C                        D

5.  Ha Long Bay is the more => most beautiful natural wonder of Viet Nam.

                            A          B                        C                  D

6.  The scenery of the Amazon rainforest in your pictures looks incredibly=> incredible.

                           A                                   B               C                       D

7.  In my opinion, foreign tourists visit Hoi An just to => forits ancient houses.

               A                                     B                        C           D

8.  Missouri is longer => the longest river in the USA, but it is shorter than the Amazon.

                      A                     B              C             D

9.  Meghalaya in India has more => the most rainy or wettest weather in the world.

                                   A          B                    C          D

10.  Lang Son is one of the coldest province => provinces in North Viet Nam.

                    A                      B             C              D

11. You mustn’t cheat in exams because the teacher will punish you when => if you do that.

                A              B                 C                                 D

12.  I’m so worried because I mustn’t => must be at home after school right now.

               A                              B                            C                        D

13. It is more => the most interesting book I have ever read.

    A              B                    C               D

14. What’s the better => most film you have ever seen?

 A             B                       C         D

15. You mustn’t => must look after the house when your parents are away

                   A                B                       C                              D

16.  It is raining heavily outside. You shouldn't => should bring your raincoat.                                                                                      

          A                 B                                  C                   D

17.  She always give => gives presents to her parents on Tet holiday.

                             A                 B   C               D

18. She will helps => help her mother decorate the house before Tet.                                                                                              

              A      B                            C                D

19.  I don't think that lucky money can bring  us good => both good and bad luck.                                                                                            

                            A                 B              C            D

20. The New Year Festival in Thailand is on => inApril. It is very hot.

                                             A                    B                C   D

ko đc vì 19001 là số nguyên tố

= 19001 vì k phân tích đc ạ?

-a nhé bạn 

=162-82+37-18+55
=80+37-18+55
=117-18+55
=99+55
=154

a.(b - c) + c.(a - b) = b - (a - c)

   a.(b - c) + c.(a - b) 

= ab - ac + ac  - cb

= (ab - bc) + (ac - ac)

= b.(a - c)

em xem lại đề bài nhé 

Trả lời tui với tui cần gấp😭

A = 100 + 98 + 96 +...+2 - 97 -95 -...- 1

Ta có : A=100+98+...+2−97−...−1�=100+98+...+2−97−...−1

=> A=100+(98−97)+...+(2−1)�=100+(98−97)+...+(2−1)

=> A=100+1+...+1�=100+1+...+1

=> A=100+1.49=100+49=149

Chúc cậu học tốt

`#3107.101107`

`x \div (-7) = 5^2 \div (-5)`

`\Rightarrow x \div (-7) = -5`

$\Rightarrow x = (-5) \cdot (-7)$

$\Rightarrow x = 35$

Vậy, `x = 35.`

\(\text{x:(-7) = 5^2}:\left(-5\right)\)

\(\text{x:(-7) = 25:(-5)}\)

\(\text{x:(-7) = -5}\)

\(\text{x = (-5).(-7)}\)

\(\text{x = 35}\)

\(\text{Vậy x=35}\)

4