x²-4y+4x-2xy+y²

=(x²-2xy+y²)+(4x-4y)

=(x-y)²+4(x-y)

=(x-y).(x-y+4)

a) 37,5.8,5-7,5.3,4-6,6.7,5+1,5.37,5

=(37,5.8,5+1,5.37,5)-(7,5.3,4+6,6.7,5)

=37,5.(8,5+1,5)-7,5.(3,4+6,6)

=37,5.10-7,5.10

=375-75

=300

b) 35²+40²-25²+80.35

=(35²+80.35+40²)-25²

=(35+40)²-25²

=(35+40+25).(35+40-25)

=100.50

=5000

phần a) bn chép sai phải ko?

số 85 ý

( lễ hội Trung Thu)

Althought there are many festivals throughout a year, I like the Mid- fall festival best because of the following reasons. Firstly, it happens in August. We can enjoy the special cake named Moon Cake with some delicious fruit and sweet. Secondly, we can wear marks and crowd to join the colorful parade on the streets. Finally, we can sing some songs about this festival such as " Ruoc den ong sao", " Dem sao"... and play some games with our friends. Therefore, the Mid-fall festival ik my favorite festival.

D, E, F sao mà vẽ thẳng hàng đc hả bn

bn có chép sai ko z?

(thích sống ở thành phố)

I like living in the city because of some reasons. Firstly, there are lots of good facilities such as famous schools and good hospitals. Secondly, it is not difficult for me to find a good job with high salary. Finally, the city has many beautiful views which we can choose to relax at the weekend. Therefore, I hope to live in the city in the future.

(thích sống ở nông thôn)

Many young people like living in the city but I like living in the countryside because of the following reasons. Firstly, the air in the countryside is fresher. Because there are fewer cars and factories in the countryside than in the city. Secondly, the scenery of the countryside is very beautiful with many green paddy fields, bamboo forests and flying kites, so it is very peaceful. Finally, people in the countyside are very kind and friendly. Therefore, I prefer living in the countryside to living in the city.

Ta có 

ab‐ba=10a+b‐10b‐a=9a‐9b=9﴾a‐b﴿ là số chính phương

=>a‐b là số chính phương

=>a‐b=1;4

xét a‐b=1=>ba=23=>ab=32

a‐b=4=>ba=37=>ab=73

Vậy ab=32;73

mk ấn nhầm

giờ mk viết lại nha

Dai Lanh- Dai Loc- Quang Nam

September 21^st,2017

Dear Trinh,

I arrived in Da Lat at 2 p.m on Thursday. My uncle met me at airport and took me home by his car.

I have visited many places like: The Valley of Love, Bao Dai's palace, The Flower Garden, ect. I have eaten a lot of local nice vegetables and the tasty fruit of Da Lat, fresh straw berries.

I will visit Dream Hill and Prenn waterfall tomorrow.

I feel very happy. The atmosphere here is very lovely and peacefull. The people here are friendly and hospitable. The foods are delicious and the sights are so beautiful.

I will leave Da Lat at 4 p.m on Saturday and I will come back home at 9 a.m on Sunday. Please pick me up the airport.

Your friend,

...........

Mon    / mieg.    / 15'.     / 1tiet 

Toan. / 10;10;9/10;9.    /8,5;9,5

Van / 9;10;8;9/9;8/9,25;8;7,5;7,75

Su/10;9/9;8/9,5

Sinh /9;10/10;10/9

Ly/10/9/ chua tra bai

Anh /10;9;9/9;10/9,3;8,8

GDCD/10/9/9,5

Tin/ 9/9/chua tra bai

1.D

2.A

3.C

4.A

5.B