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Vãi There are a total of $8\times 7\times 6\times 5\times 4=67,\!200$ ways to form a 5-digit number with distinct digits out of 0, 1, 2, 3, 4, 5, 6, 7. We claim that these can be grouped into $\binom{5}{2}\cdot 2=20$ pairs, where each pair adds up to 7777. The pairs are $(0, 7777), (1, 7776), \ldots, (4, 7773)$ and $(5, 7772), \ldots, (7, 7770)$. Thus, the sum of all the possible numbers is $20\cdot 7777=\boxed{155,540}.$ đó ko biết đúng hay sai nhé
GIUP MK VS NHE CAC BN
have you every done morning exercises ? Yes , I have
have you ever watched TV ? Yes , I have
Have you ever used a computer ? Yes , I have
Have you ever sent a text message ?...
Tự làm
:)
\(a,n^2+3⋮n-1\)
\(\Rightarrow n\left(n-1\right)+3+n⋮n-1\)
\(\Rightarrow n+3⋮n-1\)
\(\Rightarrow n-1+4⋮n-1\)
\(\Rightarrow4⋮n-1\)
...........You make the table, If i make the table, it will spent my times
That is answer:6 intergers
\(b,A=4+2^2+2^3+...+2^{20}\)
Put \(B=2^2+2^3+...+2^{20}\)
\(\Rightarrow2B=2^3+2^4+...+2^{21}\)
\(\Rightarrow2B-B=\left(2^3+2^4+...+2^{21}\right)-\left(2^2+2^3+...+2^{20}\right)\)\(\Rightarrow B=2^{21}-4\)
`\(\Rightarrow A=2^{21}-4+4=2^{21}\)
c,Consider the range of values
Put B=2.4.6.8...48
Because of B=2.4.6...10....48
=> The last digit of B is 0
Put C=1.3.5...49
Because of C= 1.3.5...49
=> The last digit of C is 5
=> B-C will have the last digit is 5
=> A have the last digit ís 5
Our school(1) has a lot of clubs and I belong to( 2) two of them: the drama group and( 3)the folk music club. In each( 4) club, you can find the same types of people. First, there is “ The Mouth”, Who can not stop talking. Then, (5) there is The Know it- all”, Who thinks that other people’s ideas(6) are Rubbish. There are also quiet types such as “ The”(7)and The Scribbler”. The Brain only speaks(8) when she has to something to say. And “ The(9)Scribbler takes a lot of notes but rarely speaks. My favorite is “ The mouse”, who smiles( 10) a Lot and seems happy to do all those boring little jobs that everyone else avoids.
Our school has a lot of clubs and I belong to two of them: the drama group and the folk music club. In each club, you can find the same types of people. First, there is “ The Mouth”, Who can not stop talking. Then, there is The Know it- all”, Who thinks that other people’s ideas are Rubbish. There are also quiet types such as “ The” and The Scribbler”. The Brain only speaks when she has to something to say. And “ The Scribbler takes a lot of notes but rarely speaks. My favorite is “ The mouse”, who smiles a Lot and seems happy to do all those boring little jobs that everyone else avoids.
Name of school( tên trường của bạn) : VD: junior hight Song Da
Reasons you like it ( lí do bạn thích nó) : VD : Because my school organized a lot of activities appealing.
Reasons you don`t like it ( lí do trường bạn không thích) : VD: Because l have a lot of schools and students are busy taking beautiful car in the garage.
|
Lake/ Sea |
Location |
|
1. Lake Baikal |
eastern Siberia (miền đông Siberia) |
|
2. Caspian Sea |
south - west Asia (Tây Nam Á) |
|
3. Lake Superior |
North America (Bắc Mỹ) |
|
4. Loch Ness |
Scotland |
|
5. Lake Nicaragua |
Central America (Trung Mỹ) |
| LAKE/SEA | LOCATION |
|
1. Lake Baikal |
In eastern Shiberia where the winters are very cold. |
|
2. Caspian Sea |
In south-west Asia. |
|
3. Lake Superior |
In North America. |
|
4. Loch Ness |
In the Scottish Highlands. |
|
5. Lake Nicaragua |
In Central America. |