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a. \(\dfrac{\left(x^2+2x\right)}{\left(x+2\right)^2}=\dfrac{x\left(x+2\right)}{\left(x+2\right)\left(x+2\right)}=\dfrac{x}{x+2}\)
b. \(\dfrac{x^2-7x+12}{x^2-6x+9}=\dfrac{x^2-3x-4x+12}{\left(x-3\right)^2}\)
\(=\)\(\dfrac{x\left(x-3\right)-4\left(x-3\right)}{\left(x-3\right)\left(x-3\right)}=\dfrac{\left(x-4\right)\left(x-3\right)}{\left(x-3\right)\left(x-3\right)}=\dfrac{x-4}{x-3}\)
c. \(\dfrac{x^2-5x+6}{x^2-x-2}=\dfrac{x^2-2x-3x+6}{x^2-2x+x-2}\)
\(=\dfrac{x\left(x-2\right)-3\left(x-2\right)}{x\left(x-2\right)+\left(x-2\right)}=\dfrac{\left(x-3\right)\left(x-2\right)}{\left(x+1\right)\left(x-2\right)}=\dfrac{x-3}{x+1}\)
d. \(\dfrac{\left(x+y\right)^2-z^2}{2\left(x+y+z\right)}=\dfrac{\left(x+y-z\right)\left(x+y+z\right)}{2\left(x+y+z\right)}=\dfrac{x+y-z}{2}\)
27. which => who
28. was => were
29. for => on
30. cooker => cook
1I thought I recognized the assistant which served us. => who
2) The twentieth century was the time when there was a lot of important events. => were
3) Tom has got the job. You must congratulate him for his success. => on
4) The cooker who is in the kitchen doesn't work anymore.=> cook
*Nhanh tay vch
a) ĐKXĐ: \(\left\{{}\begin{matrix}3x\left(x+2\right)\ne0\\x+1\ne0\end{matrix}\right.\)
<=> \(\left\{{}\begin{matrix}3x\ne0\\x+2\ne0\\x+1\ne0\end{matrix}\right.\) <=>\(\left\{{}\begin{matrix}x\ne0\\x\ne-2\\x\ne-1\end{matrix}\right.\)
b) ĐKXĐ: \(\left\{{}\begin{matrix}x^2-x+1\ne0\\2x\ne0\end{matrix}\right.\)
<=> \(\left\{{}\begin{matrix}\left(x-1\right)^2\ne0\\x\ne0\end{matrix}\right.\) <=> \(\left\{{}\begin{matrix}x-1\ne0\\x\ne0\end{matrix}\right.\) <=> \(\left\{{}\begin{matrix}x\ne1\\x\ne0\end{matrix}\right.\)
bn ơi cho mk hỏi bn lm tiếng anh hay toán mà chủ đề là tiếng anh mà bài lại là toán vậy alo????
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\(Đặt A=(n^4-3n^3+n^2-3n+1):(n^2+1) \)
\(=(n^4+n^2-3n^3+n^2-3n+10):(n^2+1)\)
\(=[n^2(n^2+1)-3n(n^2+1)+1]:(n^2+1)\)
\(=[(n^2+1)(n^2-3n)+1]:(n^2+1)\)
Để A thuộc Z thì tử phải chia hết cho mẫu mà\((n^2+1)(n^2-3n) \) chia hết cho \(n^2+1\)
=> 1 chia hết cho \(n^2+1\)
=> \(n^2+1\) thuộc Ư(1)
mà \(n^2+1>=1\) (với mọi n)
=>\(n^2+1=1\)
=>n=0
Vậy....................
1. How far is it from Beijing to Berlin?
2. How far is it from your hotel to the beach?
3. How far is it from here to the place where you live?
4. How far is it from his hometown to the place where he lives now?
5. How far is it from the park to the parking lot?
6. How far is it from here to the airport?
7. How far is it from your parent's house to your?
3. Dựa vào câu trả lời cho trước, hãy viết câu hỏi về khoảng cách
1. How far is it from Beijing to Berlin?
It's about 4576.89 miles from Beijing to Berlin.
2. How far is it from your hotel to the beach?
It's about 1 kilometre from my hotel to the beach.
3. How far is it from here to the place where I live?
It's about 500 metres from here to the place where I live.
4. How far is it from his hometown to the place where he lives now?
It is 200 kilometres from his hometown to the place where he lives now.
5. How far is it from the park to the parking lot?
It is just 200 metres from the park to the parking lot.
6. How far is it from here to the airport?
It's approximately 4 kilometres from here to the airport.
7. How far is it from my parent's house to mine?
It's about 60 kilometres from my parent's house to mine.
a .
a. =x3 -x2-4x2+4x+4x-4=(x-1)(x2-4x+4)=(x-1)(x-2)2
b. =x3+x2-6x2-6x+9x+9=(x+1)(x-3)2
c. =x3+x2+7x2+7x+10x+10=(x+1)(x+2)(X+5)
d. =x4+x3+x3+x2+x+1=x3(x+1)+x2(x+1)+x+1=(x+1)(x3+x2+x)=x(x+1)(x2+x+1).Ok