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1 tháng 3 2020

Điều kiện : a , b < 10 .

Để số 28a7b chia hết cho cả 2 và 5 b = 0.

Ta có số 28a70 . 

Để số  28a70 chia hết cho 9 thì ( 2 + 8 + a + 7 + 0 ) \(⋮9\)

                                                \(\Rightarrow\left(17+a\right)\)\(⋮9\)

                                                \(\Rightarrow\)a = 1.

Ta có số 28170.

Vậy a = 1 ; b = 0.

Hok tốt !

1 tháng 3 2020

Ta có: 

\(2x-xy+y=15\)

\(\Leftrightarrow-x\left(-2+y\right)+y-2=17\)

\(\Leftrightarrow\left(y-2\right)\left(1-x\right)=17\)

Vậy \(y-2,1-x\inƯ\left(17\right)\)

Mà \(Ư\left(17\right)=\left\{1;-1;17;-17\right\}\)

Ta có: 2x - xy + y = 15

x( 2 - y ) - ( 2 -y ) = 13

( 2 - y) ( x - 1) = 13

Tới đây e tự lập bảng ra nghe!!! hok tốt!!!

1 tháng 3 2020

Ta có AC=5; CB=7 => AB=5+7=12 cm

mà E là trung điểm => EB=12/2=6 cm

Ta có: AC + CB = AB

    hay 5+ 7 =12

Lại có : E là trung điểm AB 

Nên EB = AB/2=12/2=6

Vậy EB = 6cm 

hok tốt!!!  

1 tháng 3 2020

Số học sinh khối 6 là số chia hết cho 6;8;10

Mà BCNN ( 6; 8; 10 ) = 120, số học sinh không quá 500

=> Số học sinh có thể là 120; 240; 360; 480

Trong các số trên, số 360 chia 7 dư 3

Vậy số học sinh khối 6 là 360 

Đáp số: 360 học sinh

1 tháng 3 2020

Gọi số học sinh là a

Vì nếu xếp mỗi hàng 6 em, 8 em hoặc 10 em thì đủ 

=>BC(6,8,10)={120;240;360;480;600;...}

Mà a không quá 500 em 

=>a={120;240;360;480}

mà a chia 7 dư 4 

Ta có:

120 : 7 = 17 dư 1 ( loại)

240 : 7 = 34 dư 2 ( loại)

360 : 7=  51 dư 3 ( loại)

480 : 7 = 68 dư 4 ( nhận)

=> a=480

=>Số học sinh của trường đó là 480

IV. Complete each of the following sentences with ONE suitable word.31. During the Summer Camp, we are doing a treasure in the field.32. We are singing at the school&#39;s club: it&#39;s so exciting.33. We are a Maths test on Friday.34. I&#39;d like to become an MC, so I am taking a speaking classat the Youth Cultural Centre.35. If you are born under the of Sagittarius, you are independent,freedom-loving, and confident.36. In our Biology field , we are visiting a milk farm and we are talking with the...
Đọc tiếp

IV. Complete each of the following sentences with ONE suitable word.
31. During the Summer Camp, we are doing a treasure in the field.
32. We are singing at the school&#39;s club: it&#39;s so exciting.
33. We are a Maths test on Friday.
34. I&#39;d like to become an MC, so I am taking a speaking class
at the Youth Cultural Centre.
35. If you are born under the of Sagittarius, you are independent,
freedom-loving, and confident.
36. In our Biology field , we are visiting a milk farm and we are talking with the workers.
37. It&#39;s very to listen to a ghost story at midnight.
38. Peter often plays badminton with his friends. He also swims in his free time. He&#39;s very .
39. They are going to the library to find information. They are preparing their project.
40. Anita is a volunteer teacher at the village. She&#39;s responsible for a class. She gives instructions
about different Indian dishes.
V. Match the statement/ question in column A with the response in column B to have short exchanges,
and write the answer in each blank.
Answer A B
41. What colour of the eyes does Paul
have?
42. Would you like to have a picnic on
Sunday?
43. What sort of hair does she have?
44. Can you pass the pen, please?
45. Who&#39;s she?
46. Does she have a round face?
47. What does your new friend look like?
48. What are you doing tomorrow?
49. Who is it?
50. What do you see in the photo?
a. It&#39;s curly.

b. Yes, sure.
c. She has a round face and short black hair.
d. The students from your class are playing beach
volleyball.
e. It&#39;s my cousin, Jane.
f. Of course not. She has an oval face.
g. It&#39;s Minh, my best friend. He&#39;s kind and clever.
h. We&#39;re taking part in an art workshop.
i. Sorry, we can&#39;t. We&#39;re visiting our grandparents.
j. They&#39;re blue.

Nguyen Thi Thu Hien – Kieu Phu School
VI. Make sentences using the words and phrases given.
51. We/ visit/ milk farm/ do/ treasure hunt/ field/ tomorrow.
52. He/ play/ basketball/ have/ barbecued/ his friends/ Sunday evening.
53. You/ do/ anything/ this Saturday evening?
54. Our teacher/ ask/ us/ write/ emails/ English.
55. He/ play/ basketball/ very well/ and/ he/ sporty.
VII. Write questions for the underlined part.
56. They are visiting a milk farm on Saturday.
57. I&#39;m going to the judo club with my brother.
58. I&#39;m not going to your party because I visit my grandparents.
59. We&#39;re working on our school project.
60. She understands things very quickly and easily.

VIII. Find and correct the mistake in each sentence.
61. He isn&#39;t very tall so he is kind and friendly.
62. I&#39;m playing football on my team.
63. We are going to Han River to watch the international firework competition, but you can watch it live on TV.
64. She works as a volunteer teacher to a village and everyone loves her.
65. I&#39;m going to the river with my parents watching the firework display.

IX. Complete the conversation, and then practise it with your partner.
Linda Where&#39;s Tom?
Peter (66) in the sport centre.
Linda The sport centre? I think he is at the judo club. Do you think so?
Peter (67) . And Tom&#39;s very good at judo.
Linda Do you have a new classmate this morning?
Peter Yes, (68) a round face and long black hair. Her name&#39;s Susan.
Linda Would you introduce her to me?
Peter Yes, (69) . I think she&#39;s very (70) because she paints nice pictures.
X. Complete the text with the words in the box.

Nguyen Thi Thu Hien – Kieu Phu School

she&#39;s fair long athlete British
arms plays eyes swimmer legs

Vicky Gates is a professional football player. She has (71) , (72) hair and blues eyes. She has
long legs and very strong (73) . Vicky is American.
Anita Mather is a professional sportswoman. She (74) basketball. She has very long (75) and
(76) very tall.
Joana Smith is an international (77) . She has short, fair hair and green eyes. She&#39;s short but she has very
big shoulders. She&#39;s (78) .
Jo Kelly is an (79) . She has long, dark hair and blue (80) . She has very long legs. Jo is
from Nigeria.

0

\(a,1.2155-\left(174+2155\right)+\left(-68+174\right)\)

\(=2155-2155-174+174-68\)

\(=-68\)

\(b,-25.72+25.21-49.25\)

\(=25\left(-72+25-49\right)\)

\(=25.\left(-96\right)\)

\(=-2400\)

Mik nghĩ  đề của bn sai rùi!  (3 − )?????

hok tốt!!!

1 tháng 3 2020

=-10-(-5)=-8-(-3)

=15=11(vô lí)

sai đề bài nha :)

1 tháng 3 2020

Vì số học sinh nam và nữ không bằng nhau nên không thể chia số học sinh như nhau được :

                                     28 = 7 x 4 = 2 x 14

\(\Rightarrow\) 7 nhóm , mỗi nhóm có 4 học sinh hoặc 4 nhóm , mỗi nhóm có 7 học sinh ...

                                     24 = 2 x 12 = 4 x 6 = 3 x 8

\(\Rightarrow\) Ta thấy : Trong hai cách phân tích thì cách phân tích 4 x 7 và 4 x 6 có chung thừa số 4 .

Cách phân tích 2 x 14 và 2 x 12 có chung thừa số 2 .

\(\Rightarrow\) Ta có thể chia thành 4 tổ , trong đó, mỗi tổ có 7 nam và 6 nữ .

Ta cũng có thể chia thành 2 tổ , trong đó có 14 nam và 12 nữ .

\(\Rightarrow\) Cách chia thành 4 tổ thì số học sinh ít nhất .

Bạn tham khảo bài của mình nhé !! 

1 tháng 3 2020

Tính tất cả ước chung của 28 và 24.

Tính ước chung lớn nhất

1 tháng 3 2020

nếu đề bài cho tìm x,y nguyên thì bạn chặn bảng làm th