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\(x^{15}=x\)
\(\Rightarrow x^{15}-x=0\)
\(\Rightarrow x.\left(x^{14}-1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x^{14}-1=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x^{14}=0+1=1\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x=1\end{cases}}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{x+1}{2}=\frac{8}{x+1}\Rightarrow\left(x+1\right)^2=8.2\)
=>(x+1)2=16
=>x+1=\(\sqrt{16}\)
=>x+1=4
=>x=3
![](https://rs.olm.vn/images/avt/0.png?1311)
\(x+\left(x+1\right)+\left(x+2\right)+...+19+20=20\)
\(\Leftrightarrow x+\left(x+1\right)+\left(x+2\right)+...+19=0\)
\(\Leftrightarrow\frac{x\left(19+x\right)}{2}=0\)
\(\Leftrightarrow x\left(x+19\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=0\\x+19=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=0\\x=-19\end{cases}}\)
Mà \(x\ne0\)nên \(x=-19\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có: x(1+30%)=-1,31
⇒ \(\dfrac{13}{10}\)x =-1,31
⇒ x =-1,31 : \(\dfrac{13}{10}\)
⇒ x = -\(\dfrac{131}{130}\)
x + 30% x = -1,31
\(x+\dfrac{30}{100}x=-1,31\)
x+0,3x=-1,31
x.(0,3+1)=-1,31
x.1,3=-1,31
\(x=\dfrac{-1,31}{1,3}\)
\(x=-\dfrac{131}{130}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
1:x:x+9x223=2011
1/x:x+9.223=2011
1/x+9.223=2011
1/x+2007=2011
1/x=2011-2007
1/x=4
x=1/4
1 : X : X + 9.223 = 2011
1 : X + X = 2011 - 9.223
1 : X + 1 : X = 4
( 1 + 1 ) : X = 4
2 : X = 4
X = 2 : 4
X = 0,5
Nếu mình đúng thì các bạn k mình nhé
![](https://rs.olm.vn/images/avt/0.png?1311)
\(-\dfrac{x}{2}=-\dfrac{8}{x}\)
<=> x2 = 16
<=> x = 4 hoặc x = -4
Vậy x = 4 hoặc x = -4
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\Leftrightarrow x-\left[3-x+3+x-2\right]=0\)
=>x=4
![](https://rs.olm.vn/images/avt/0.png?1311)
x(x-1)= 154/15*100=3080/3
=>3x(x-1)=3080
=> 3x^2 -3x-3080=0
delta = b^2-4ac = (-3)^2-4.3.(-3080)=36969
=> x= (-b^2-căn dellta )/(2a) và x=(-b^2+ căn delta) /(2a)