40 ngày đánh số trang: 

    40 x 15 = 600 ( trang )

muốn đánh xong trong 30 ngày thì mỗi ngày cần đánh số trang là :

     600 : 30 = 20 ( trang )

                   Đ/S : 20 trang

3ⁿ⁺²+3ⁿ-2ⁿ⁺²-2ⁿ

=3ⁿx3²+3ⁿ-2ⁿx2²-2ⁿ

=3ⁿx(3²+1)-2ⁿx(2²+1)

=3ⁿx10-2ⁿx5

Vì 3ⁿx10 chia hết cho 10(n nguyên dương)

    2ⁿx5 chia hết cho 10(n nguyên dương)

Vậy 3ⁿ⁺²+3ⁿ-2ⁿ⁺²-2ⁿ chia hết cho 10

-100 , ủng hộ mk nha

mk moi hoc lop 5 sory

VI:use the correct form of words

1.there are sixteen desks in.......my.....room.(I)

2.there are twenty books on the ....bookshelf....(book)

3.he gets ............dressed............and goes to school.(dress)

Bài 4:

    |x|<5

=>x thuộc {-4;-3;-2;-1;0;1;2;3;4}

    |x|<7

=>x thuộc {-6;-5;-4;-3;-2;-1;0;1;2;3;4;5;6}

Bài 5:

   (-25).6.4                                                                (54+47-69)-(54+47)

={(-25)*4}*6                                                            =54+47-69-54-47                                                         

=-100*6                                                                 =(54-54)+(47-47)+(-69)

=-600                                                                    =0+0+(-69)

                                                                            =-69

  63-9.(20+7)                                                            21.45+21.(-33)-21.22

=63-9.27                                                                =21.{45+(-33)}-21.22

=63-243                                                                 =21. 12- 21.22                                                              

=-180                                                                    =21.(12-22)

                                                                            =21.(-10)

                                                                            =-210

V. Choose the best word in brackets to complete the sentences :

1. My friend is hot. He(would like / like want) a cold water.

2. ( Does / Do / Is ) she like some bananas?

3. He ( feels / does / wants ) tired.

4. What (am / is / are) your favorite food?

5. I (don't / doesn't / am not) like carrots and lettuce.

6.We (don't want / want / wants) some vegetables.

7.How (many / much / about) are these eggs?

8.(How many / How much) rice does his father want?

9.(What / How / Where) color is her hair?

10. What (are you doing / are you going to do)?- I'm writing the letter.

11. They (are moving / are going to move) to her new house next week.

12. Let's (go / going / to go) to HCM city.

13. How (many / often / long ) does she go to school? - Every day.

14. What about ( to go / go / going ) to the movies?

15. I'm going to stay ( in /for / with ) my aunt and uncle.
16. Tokyo is bigger ( as / to /than ) London.

17. How many ( names / countries / languages ) can you speak ?- Two.
18. Ha Noi is the ( capital / city / town ) of Viet Nam.
19. Bruce is from Australia. He speaks ( Australian / French / English).
20. Laura is Canadian. He is from ( France/ China / Canada)

p/s: Câu 19 nếu xét về mặt thực tế thì là 2 ngôn ngữ ( Australian, English ), nếu xét về câu đề thì chỉ có Australian thoi nha :D