ta có:

\(\hept{\begin{cases}126=2.3^2.7\\210=2.3.5.7\end{cases}\Rightarrow UCLN\left(120,210\right)=2.3.7=42}\)

vậy có nhiefey nhất 42 tổ

mỗi tổ khi đó có : \(\hept{\begin{cases}126:42=3\text{ nữ}\\210:420=5\text{ nam}\end{cases}}\)

a) T/C hóa học

b) T/C vật lí

c) T/C hóa học

Đâu là tính chất vật lý, đâu là tính chất hóa học?

a) Đường tan vào nước : Hóa học

b) Nước hóa hơi : Vật lý

c) Nến cháy thành khí carbon dioxide và hới nước : Hóa học

TL:

vì nó có ƯCLN của tỉ số và mẫu số là 1

_HT_

tại sao mk ko đăng câu hỏi đc, ng ta bảo phải nhờ quản trị viên duyệt trước khi đăng, mk chờ mãi mà chẳng đăng đc. các bn giúp mk mk cần gấp lắm

ta có :

\(C=\left(5+5^2\right)+\left(5^3+5^4\right)+..+\left(5^{19}+5^{20}\right)\)

\(=5.6+5^3.6+5^5.6+..+5^{19}.6\)

thế nên C chia hết cho 6

 C= 5+5^2+5^3+...+5^20. 

C=(5+5^2)+(5^3+5^4)...+(5^19+5^20)

C=30+(5^2.5+5^2.5^2)+...+(5^18.5+5^18.5^2)

C=30+5^2.30+...+5^18.30

Vì 30:6 ->30+5^2.30+...+5^18.30->C:6

John’s daily routine is a little boring, but he s it. He usually gets up at about 6:00 or 6:30 in the morning after his alarm wakes him up. First, he brushes his teeth and shaves and washes his face. Then he gets dressed and goes downstairs to have breakfast with his family. He always has juice, cereal, and lots of fruit. He takes a bus to work because he doesn’t to drive, and he always arrives at his office before 8:00. Five o’clock is his favorite time of the day because he finishes work and hurries back home to see his wife and children again. He has two boys, Tomas, who is 6 years old and Patrick, who is 8. They eat dinner together in their dining room at around 6:00, and after that he spends time with his wife and kids at home. They really enjoy watching their favorite shows together. In addition, two or three times a week he does exercise in the evening, so he can stay strong and healthy. He thinks that this is very important. Finally at about 9:30, he goes to bed, reads for a while, and then falls asleep. Sure, some people think that his routine is a little boring, but on weekends he loves to fly airplanes for fun! It’s his favorite hobby.

Câu thứ 2: get -> gets , wake->wakes

Câu thứ 3:brush-> brushes, shave->shaves, wash-> washes

Câu thứ 4:get dressed->gets dressed, go->goes

Câu 6:take->takes, arrive-> arrives

Câu 7:finish->finishes, hurry->hurries, see->sees

Câu 9:spend->spends

Câu 11: do exercise-> does exercise

Câu 12: think->thinks

Câu 13: go->goes, read->reads, fall asleep->falls asleep

Câu 14:love->loves

Câu 15: hobby->hobbies

Mình tìm đủ 20 lỗi ngữ pháp rồi đóa bạn, nếu còn thiếu sót gì thì thông cảm cho mình nha🤍Học tốt!

My cousin, Peter, (have) has a dog. It (be) is an intelligent pet with a short tail and big black eyes. Its name (be) is Kiki and it () s eating pork. However, it (never/ bite) never bites anyone; sometimes it (bark) barks when strange guests visit. To be honest, it (be) is very friendly. It (not/ ) does not |doesn’t  eating fruits, but it (often/ play) often plays with them. When the weather (become) becomes bad, it (just/ sleep) just sleeps in his cage all day. Peter (play) plays with Kiki every day after school. There (be) are many people on the road, so Peter (not/ let) does not let/doesn’t let the dog run into the road. He (often/ take) often takes Kiki to a large field to enjoy the peace there. Kiki (sometimes/ be) is sometimesnaughty, but Peter loves it very much.

XCDXSZSXDFDCXSZXSDFTDCXSZXSDFRTYU

Mary is a teacher. She teaches English. The children love her and they learing a lot from her. Mary comes home at 11.30 and has lunch. Then she sleeps for an hour. In the afternoon she goes swimming or she clears her house. Sometime she visits her aunt and drinks tea with her. Every Sunday she goes the shopping with her friends.

Số ước chung của 18 và 35 là 1

HT

TL

18 = 2 . 3²

35 = 5 . 7

=> ƯCLN(18 ; 35) = 1

=> Ư(1)= {-1 ; 1}

HT

=>ƯC(18;35)={-1;1}