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![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
a: Để A là số nguyên thì \(x+1⋮3\)
=>x=3k-1, với k là số nguyên
b; Để B là số nguyên thì \(x-1\in\left\{1;-1;17;-17\right\}\)
hay \(x\in\left\{2;0;18;-16\right\}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
a: Để A là phân số thì n+1<>0
hay n<>-1
b: Để A là số nguyên thì \(n+1\in\left\{1;-1;5;-5\right\}\)
hay \(n\in\left\{0;-2;4;-6\right\}\)
Cho phan so A = n+1/n-3 (nCZ)
a) Tim cac gia tri cua n de A la phan so
b) Tim n de A co gia tri nguyen
![](https://rs.olm.vn/images/avt/0.png?1311)
a) Để A = \(\frac{n+1}{n-3}\) là phân số thì \(n-3\ne0\)hay\(n\ne3\)
b) Để A là số nguyên thì:
\(n+1⋮n-3\)
mà \(n-3⋮n-3\)
\(\Rightarrow\left(n+1\right)-\left(n-3\right)⋮n-3\) hay\(4⋮n-3\)
\(\Rightarrow n-3\inƯ_{\left(4\right)}\)
\(\Rightarrow n\in\){4;2;5;1;7;-1}
![](https://rs.olm.vn/images/avt/0.png?1311)
Hoàn tất đoạn văn sau, sau đó trả lời câu hỏi bên dưới
Quang s camping(1)_______at_____the weekend, he often go camping(2)_____on_____the mountains. He usually goes(3)____with______ his friend. Quang and his fried always wear strong boots(4)_____and______warm clothes. (5)______They_____always take food, water and a camping stove. Sometimes, they (6)______camp_______overnight.
* Questions:
1. What does Quang s?
He s camping.
2. Where does he often go camping?
He often goes camping on the mountains.
3. When does he go?
On weekend.
4. Who does he usually go with?
He usually goes with his friend.
5. What do they always wear?
Quang and his fried always wear strong boots and warm clothes.
6. What do they always take?
They always take food, water and a camping stove.
7. Do they camp overnight?
Yes, they do.
![](https://rs.olm.vn/images/avt/0.png?1311)
3.a) tổng các cs của tử là 3 nên chia hết cho 3
b) tổng các cs của rử là 9 nên chia hết cho 9
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,\frac{x+6}{x+1}\)
\(\left\{\left(x+6\right)-\left(x+1\right)\right\}⋮x+1\)
\(5⋮x+1\)
\(x+1\inƯ_{\left(5\right)}=\left\{-5;5;1;-1\right\}\)
\(=>x\inƯ_{\left(5\right)}=\left\{-6;4;0;-2\right\}\)
\(b,\frac{x-2}{x+3}\)
\(\left\{\left(x+3\right)-\left(x-2\right)\right\}⋮x+3\)
\(5⋮x+3\)\(=>x+3\inƯ_{\left(5\right)}=\left\{-5;5;-1;1\right\}\)
\(=>x\in\left\{-8;2;-4;-2\right\}\)
b)
ĐKXĐ: \(x\ne-\dfrac{3}{2}\)
Để phân số \(B=\dfrac{4x+1}{2x+3}\) là số nguyên thì \(4x+1⋮2x+3\)
\(\Leftrightarrow4x+6-5⋮2x+3\)
mà \(4x+6⋮2x+3\)
nên \(-5⋮2x+3\)
\(\Leftrightarrow2x+3\inƯ\left(-5\right)\)
\(\Leftrightarrow2x+3\in\left\{1;-1;5;-5\right\}\)
\(\Leftrightarrow2x\in\left\{-2;-4;2;-8\right\}\)
hay \(x\in\left\{-1;-2;1;-4\right\}\)(thỏa ĐK)
Vậy: \(x\in\left\{-1;-2;1;-4\right\}\)