Quá dễ này bạn !!!

Xét vế phải là (2^y+1)(2^y+2)

TH1: y chẵn => 2^y chia 3 dư 1 => 2^y+2 chia hết cho 3 (1)

TH2: y lẻ => 2^y chia 3 dư 2 => 2^y+1 chia hết cho 3 (2)

Từ (1) và (2) thì với mọi y thuộc N thì (2^y+1)(2^y+2) chia hết cho 3

=> vế phải cũng chia hết cho 3

Nếu x>=1 => 3^x chia hết cho 3; 89 ko chia hết cho 3=> vế trái ko chia hết cho 3=> LOẠI

Nếu x=0 => 3^0+89=90 (TMĐK) => y=3

Vậy x=0 và y=3.

lili ơi cái này đậu phải trả lời lớp 6 đâu 

mặc dủ mình k biết làm nhưng mình chắc câu trả lời của bạn hình như k phải cách giải lớp 6 

nếu mình sai mình xin lỗi

bn có thể tham khảo cách này

Gọi I là giao điểm của các tia phân giác \(\widehat{KBC}\)và\(\widehat{KCB}\).Khi đó KI là tia phân giác của \(\widehat{BKC}\)

Mặt khác, tam giác KBC có BKC=120^o (vì \(\widehat{KBC}=40^o,\widehat{KCB}=40^o\))

Do đó \(\widehat{BKI}=\widehat{CKI}=\widehat{BKE}=\widehat{CKD}=60^o\)

Xét \(\Delta\)BKI và\(\Delta\)BKE ta có:\(\hept{\begin{cases}\widehat{B_2}=\widehat{B_3}\left(gt\right)\\BK\left(chung\right)\\\widehat{BKI}=\widehat{BKE}=60^o\end{cases}}\)

Suy ra \(\Delta\)BKI=\(\Delta\)BKE (g.c.g) =>KE=KI (1)

Tuong tự ta có KD=KI (2)

Từ (1) và (2) suy ra KE=KD hay \(\Delta\)KED cân tại K

Mặt khác,\(\widehat{EKD}=120^o=\widehat{BKC}\)(đối đỉnh)

Do đó \(\widehat{KED}=\widehat{KDE}=\frac{180^o-120^o}{2}=30^o\)

Ta có:

ACB=ACE+BCE

mà ACB=30 độ;ACE=10 độ=>BCE=20 độ

C/m tương tự với góc C ta có CBD=40 độ

Xét tam giác CBK ta có:

KCB + KBC + CKB=180

=> CKB= 180 - KCB - KBC

CKB=180-20-40

      =120 độ

mà CKB đối đỉnh với DKE nên DKE=120 (mình ko viết dc kí hiệu góc nha)

a) Ta có: sin30=cos60, sin50=cos40

    Mà cos30 < cos38 < cos40 < cos60 < cos80

    Nên cos30 < cos38 < sin50 < sin30 < cos80

b) Ta có: tan75=cot15, tan63=cot27 => cot11 < tan75 < cot20 < tan63 (1)

         và: sin49=cos41 => cos30 < sin49 (2)

    Lại có: cot11=tan69 > tan49= sin49:cos49 > sin49 (do cos49<1) (3)

    Từ (1), (2) và (3) suy ra: cos30 < sin49 < cot11 < tan75 < cot20 < tan63

TA CÓ   \(\sin30\)= \(\cos60\)

             \(\sin50=\cos40\)

---->>  \(\cos30< \cos38< \cos40< \cos60< \cos80\)

------>> \(\cos30< \cos38< \sin50< \sin60< \cos80\)

Cái kia làm tương tự nhoa

Bạn xin 1 cái k

Poverty is no shame

My parents died in a traffic accident when I was ten years old, so I grew up with my grandmother who was too old and weak to work. I had to leave school and did odd jobs to earn a living: selling lottery kets, washing dishes and doing babysitting. When I was 15, my grandma encouraged me to attend evening classes, so I could improve my literacy and job prospects.

After lots of hardship and effort, I completed secondary education and passed a challenging exam to enter Medical University, which is the dream of many students. However, I could not pay the tuition fees and had to reject the offer. The door to a new life was closed before me. I was completely disappointed and saw only gloomy days ahead.Then something incredible happened: I was awarded a scholarship from The Thanh Nien for college students from poor families. This was really a turning point in my life because I could start my university studies and hope for a better future.

Six years of hard work at the university and of trying to live on a very tight budget came to an end at last. Now I am working as a doctor at a hospital, but I will never forget those difficult days. I am planning to set up and run a charitable organisation to help poor students, as a way to acknowledge other people for supporting me.

I've told my own story hoping to encourage other people me to overcome hard times. Don't let poverty defeat you and destroy your hopes for a better future. This is my motto.

Mong cô duyệt bái cho em ạ !

I am Kim Lee. I am now 17 years old. When I was at the age of 15 I started getting acne.

My face looked terrible and I always felt depressed and insecure about appearance. Then I came to see one of my best friends, who always gave me good advice and asked her for advice. She told me that I should wash my face several times a day and try different anti­acne products, squeeze pimples often. But this way doesn't help a lot. The result of that was 60% of my face was covered with acne.

I found a website advertising an effective way to remove acne, and they advised me to see Dr Kangnam. Dr Kangnam gave me a detailed plan to remove acne on my face. First, he advised me to wash my face only twice a day because washing face too often may cause skin irritation. Second, I have to take prescription medicine. Third, I had to follow a healthy diet. Dr Kangnam also advised me not to stay up late. After six months acne clears up. And now I feel very happy and confident.

I am Kim Lee. I am now 17 years old. When I was at the age of 15 I started getting acne.

My face looked terrible, I always felt depressed and insecure about appearance. Then I came to see one of my best friends, who always gave me good advice. I asked her for some advice. She told me that I should wash my face several times a day and try different anti­acne products, squeeze pimples often. But this way didn’t help a lot. The result was that 60% of my face was covered with acne.

I found a website advertising an effective way to remove acne, and they advised me to see Dr Kangnam. Dr Kangnam gave me a detailed plan to remove acne on my face. First, he required me to wash my face only twice a day because washing face too often may cause skin irritation. Second, I had to take prescription medicine. Third, I was told to follow a healthy diet, including enough nutrients, eating lots of vegetables, drinking 2 litter of water every day and not consuming too much spicy hot food. Dr Kangnam also said that I shouldn’t stay up late, sleep at least 6 hours a day if I wanted my face to be smooth. After six months of following his instruction, acne clears up amazingly, my skin is smoother and I feel so happy and confident.

Gọi tổng số cây mà 4 đội trồng được là T, ta có:

Đội 1 trồng được 1/3T

Đội 2 trồng được 1/4 số cây của 3 đội kia, tức 3 đội kia chiếm 4 phần thì số cây đội 2 là 1 phần. Và số cây 3 đội kia trồng được cộng với số cây đội 2 trồng được chính là tổng số cây 4 đội trồng được, tức là T. Vậy Đội 2 trồng được 1/5T

Đội 3 trồng được 1/5 số cây của 3 đội kia, phân tích tương tự phần trên ta được Số cây đội 3 trồng được bằng 1/6T

Đội 4 trồng được 18 cây tương ứng với: T - 1/3T - 1/5T - 1/6T = 9/30T = 18

Vậy T = 18:9/30 = 60 (cây)

Đáp số: 60 cây.

đuong nhien la 60

yuuyuuuuuuuuuuuuuuuuudr

uuuuuuuu7

^{rruurrrrrrrrrrrrrrrrr7\(x = {-b \pm \sqrt{b^2-4ac} \over r2a}ddd\)}

r2.tt nha

10-897eerret667

công thức để làm :10ⁿ+8=9.11...112 (có n-1 chữ số 1, n>1)

a chia hết cho bⁿ thì a phải chia hết cho b

11...12 luôn ko chia hết cho 7 (n chữ số 1 , n khác 2 )

ta có: 10²⁰²¹+8=9.11...112(2020 chữ số 1)

vì 9 ko chia hết cho 7 , 11...112 ko chia hết cho 7 và (9,11...12)=1 suy ra 9.11...112 ko chia hết cho 7 suy ra 10²⁰²¹+8 ko chia hết cho 7 suy ra điều cm trên là sai

nếu mình sai cho mình xin lỗi nha

suy7 nha

Dear Anne(Hà Lam).

I received your email last week, in which you asked me about my city New York in 2050. There are different ideas about this question. I thought it in a few days, and now I can give you two predictions.

Let's take a look at an optimis viewpoint. In 2050 New York will become a more liveable city than ever before for lots of reasons. The city authorities have built a very careful plan to promote self-driving electric taxis to deal with crowded public transport. In addition, the city dwellers are encouraged to use city's building roofs for gardens fertilised with compose in order to recycle rubbish and reduce pollution. The government will also build offshore windfarms to replace ageing electricity network.

On the other hand, pessimis people think that the city life won't be a safe place to live in because the government cannot control the use of guns, and therefore the crime rate will be higher. People's life will also continue to be threatened because of natural disasters such as floods, storms, earthquakes. The effects of global warming have great impacts on the city dwellers.

That's all about my answer to your question. I hope you will be satisfied with it, Nam.

Best wishes,

Wonie(Quyên)

tham khảo ạ

Dear Bich

Your last email asked me about my city Ha Noi in 2050. Well, but I'm busy and have no time to reply you soon. Today I am writing to you about that question. There are different ideas about this question. I thought about it in a few days, and now I can give you some predictions.

Let's take a look at optimis aspects. In 2050 Ha Noi will become a more modern city for lots of reasons. High technology has been applied in our lives. The robots will replace us for many jobs such as manufacturing, farming, etc. Smart cars which will be commonly used in the road. They will help human beings to decrease the accidents as well as traffic jams.

On the contrary, pessimis people think that the city life will be a dangerous place to live in because the environment is completely polluted. The effects of global warming have great impacts on the city dwellers, higher temperature in the summer and colder climate in the winter. There are a lot of means of transport so that emission from them cause air pollution. Our health will be threatened because of low air quality index.

That's all about my thoughts about your question. I hope you will be satisfied with it, Bich.

Best wishes,

Chau