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LT
2
8 tháng 9 2019
\(4x^2-6x-16⋮x-3\)
\(\Leftrightarrow4x^2-12x+6x-18+2⋮x-3\)
\(\Leftrightarrow4x\left(x-3\right)+6\left(x-3\right)+2⋮x-3\)
\(\Leftrightarrow\left(x-3\right)\left(4x+6\right)+2⋮x-3\)
Mà \(\left(x-3\right)\left(4x+6\right)⋮x-3\)
\(\Rightarrow2⋮x-3\)
\(\Rightarrow x-3\inƯ\left(2\right)=\left\{\pm1;\pm2\right\}\)
làm nốt
8 tháng 9 2019
cách 2:
4x^2-6x-16 x-3 4x+6 4x^2-12x - 6x-12 6x-18 - 2
Để \(4x^2-6x-16\)chia hết cho x-3
\(\Leftrightarrow2⋮x-3\)
\(\Leftrightarrow x-3\inƯ\left(2\right)=\left\{\pm1;\pm2\right\}\)
Làm nốt
14 tháng 10 2018
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
30 tháng 11 2017
\(Đặt A=(n^4-3n^3+n^2-3n+1):(n^2+1) \)
\(=(n^4+n^2-3n^3+n^2-3n+10):(n^2+1)\)
\(=[n^2(n^2+1)-3n(n^2+1)+1]:(n^2+1)\)
\(=[(n^2+1)(n^2-3n)+1]:(n^2+1)\)
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....................
9 tháng 12 2017
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. \(\dfrac{\left(x+y\right)^2-z^2}{2\left(x+y+z\right)}=\dfrac{\left(x+y-z\right)\left(x+y+z\right)}{2\left(x+y+z\right)}=\dfrac{x+y-z}{2}\)
9 tháng 12 2017
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: \(\left\{{}\begin{matrix}x^2-x+1\ne0\\2x\ne0\end{matrix}\right.\)
<=> \(\left\{{}\begin{matrix}\left(x-1\right)^2\ne0\\x\ne0\end{matrix}\right.\) <=> \(\left\{{}\begin{matrix}x-1\ne0\\x\ne0\end{matrix}\right.\) <=> \(\left\{{}\begin{matrix}x\ne1\\x\ne0\end{matrix}\right.\)
DM
20 tháng 11 2016
1) I (go) will go/ am going to go to the theater this evening.
2) (the film/ start) Is the film starts at 3 p.m ?
3) I (not, go) won't go out this evening. I (stay) will stay home.
4) The art exhibition (open) opens on December 1st and (finish) finishes on December 8th.
5) The train (leave) leaves at 7 o'clock tomorrow morning.
6) The match (start) starts at 5 o'clock this afternoon.
7) The coach (arrive) arrives in Hue at noon.
8) John and Sarah (get) will get married next month.
9) I (not, go) am not going away for my summer vacation this summer.
10) I must get to the banhk before it (close) closes .
-> Các câu dù bản chất chia thì tương lai mà chia thì quá khứ vì những câu đó chỉ thời gian biểu -> chia thì HTĐ
22 tháng 11 2016
- will go / am going to go
- Is...........start.........
- ...........won't go.............. will stay ......
- ..........opens..............finishes
- ......leaves.....
- starts
- arrives
- will get
- am not going
- closes
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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