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\(a,\Leftrightarrow x^3=\dfrac{20}{3}\Leftrightarrow x=\sqrt[3]{\dfrac{20}{3}}\\ b,\Leftrightarrow x-1=9\Leftrightarrow x=10\\ c,\Leftrightarrow\left[{}\begin{matrix}x-1=5\\x-1=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-4\end{matrix}\right.\\ d,\Leftrightarrow2x+1=5\Leftrightarrow x=2\\ e,\Leftrightarrow2x-4=4\Leftrightarrow x=4\)
Câu a) xem lại đề giùm nhé em
b) \(\left(x-1\right)^3=9^3\)
\(x-1=9\)
\(x=10\)
Vậy \(x=10\)
c) \(\left(x-1\right)^2=25\)
\(x-1=5\) hoặc \(x-1=-5\)
* \(x-1=5\)
\(x=6\)
* \(x-1=-5\)
\(x=-4\)
Vậy \(x=-4\); \(x=6\)
d) \(\left(2x+1\right)^3=125\)
\(\left(2x+1\right)^3=5^3\)
\(2x+1=5\)
\(2x=4\)
\(x=2\)
Vậy \(x=2\)
e) Sửa đề: \(\left(2x+4\right)^3=64\)
\(\left(2x+4\right)^3=4^3\)
\(2x+4=4\)
\(2x=0\)
\(x=0\)
Vậy \(x=0\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(3\left(2x-5\right)+125=134\)
\(\Leftrightarrow3\left(2x-5\right)=9\)
\(\Leftrightarrow2x-5=3\)
\(\Leftrightarrow2x=8\Leftrightarrow x=4\)
b) \(\left(2x+5\right)+\left(2x+3\right)+\left(2x+1\right)=27\)
\(\Leftrightarrow6x+9=27\)
\(\Leftrightarrow6x=18\Leftrightarrow x=3\)
d) \(27\left(x-27\right)-27=0\)
\(\Leftrightarrow27\left(x-27\right)=27\)
\(\Leftrightarrow x-27=1\Leftrightarrow x=28\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có \(5^x=125\)
\(\Rightarrow5^x=5^3\Rightarrow x=3\)
Vậy x = 3
b,\(3^{2x}=81\)
\(\Rightarrow3^{2x}=3^4\Rightarrow2x=4\Rightarrow x=2\)
Vậy x = 2
c,\(5^{2x-3}-2.5^2=5^2.3\)
\(\Rightarrow5^{2x-3}=5^2.3+5^2.2\Rightarrow5^{2x-3}=5^2.\left(2+3\right)\Rightarrow5^{2x-3}=5^3\)
\(\Rightarrow2x-3=3\Rightarrow2x=6\Rightarrow x=3\)
Vậy x = 3
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
2x - 3 = 54 : 52
2x - 3 = 54 - 2 = 52 = 25
2x = 25 + 3
2x = 28
x = 28 : 2
x = 14
5x + 2 = 53 . 125
5x + 2 = 53 . 53 = 53 + 3 = 56
=> x = 6 - 2
x = 4
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có : (x - 5)4 = (x - 5)6
=> (x - 5)4 - (x - 5)6 = 0
=> (x - 5)4 (1 - (x - 5)2) = 0
\(\Leftrightarrow\orbr{\begin{cases}\left(x-5\right)^4=0\\1-\left(x-5\right)^2=0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}\left(x-5\right)=0\\\left(x-5\right)^2=1\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=5\\x-5=1;-1\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=5\\x=4;6\end{cases}}\)
Vậy x = {4;5;6}
Tìm x thuộc N:
2x.4=128
2x =128:4
2x =32
x =32:2
x =16
b.x.15=x
x thỏa mãn điều kiện:0,1
c.(2x+1)3=125
(2x+1)3=53
==>2x+1=5
2x =5-1
2x =4
x =4:2=2
phần d mk chưa hiểu lắm
![](https://rs.olm.vn/images/avt/0.png?1311)
\(3x\left(2x+1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}2x+1=0\\3x=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}2x=-1\\x=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=-\frac{1}{2}\\x=0\end{cases}}\)
\(\frac{\frac{6}{5}+\frac{6}{35}-\frac{6}{125}-\frac{6}{2009}-\frac{6}{2011}}{\frac{7}{5}+\frac{7}{35}-\frac{7}{125}-\frac{7}{2009}-\frac{7}{2011}}\)
\(=\frac{6.(\frac{1}{5}+\frac{1}{35}-\frac{1}{125}-\frac{1}{2009}-\frac{1}{2011})}{7.(\frac{1}{5}+\frac{1}{35}-\frac{1}{125}-\frac{1}{2009}-\frac{1}{2011})}\)
\(=\frac{6}{7}\)
Tìm x
\(a,3x(2x+1)=0\)
\(\Rightarrow\hept{\begin{cases}3x=0\\2x+1=0\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x=0\\x=\frac{-1}{2}\end{cases}}\)
Vậy \(x=0\)hoặc \(x=\frac{-1}{2}\)
\(b.\frac{2}{3}-\frac{1}{3}(x-\frac{3}{2})-\frac{1}{2}(2x+1)=5\)
\(\frac{2}{3}-\frac{1}{3}x+\frac{1}{2}-x-\frac{1}{2}=5\)
\(\frac{2}{3}+\frac{1}{2}-\frac{1}{2}-x(\frac{1}{3}+1)=5\)
\(\frac{4}{3}x=\frac{2}{3}-5\)
\(\frac{4}{3}x=\frac{-13}{3}\)
\(x=\frac{-13}{3}\div\frac{4}{3}\)
\(x=\frac{-13}{4}\)
Chúc ban học tốt
![](https://rs.olm.vn/images/avt/0.png?1311)
\(5^{x+1}=125\)
\(5^{x+1}=5^3\)
\(x+1=3\)
\(x=2\)
b, \(5^{2x-3}-2.5^2=5^2.3\)
\(5^{2x-3}=5^2.\left(3+2\right)\)
\(5^{2x-3}=5^3\)
\(2x-3=3\)
\(x=3\)
c, \(2^x=32\)
\(2^x=2^5\)
\(x=5\)
Chúc em học tốt.
![](https://rs.olm.vn/images/avt/0.png?1311)
( 2x + 1 ) \(^3\)= 125
( 2x + 1 ) = \(\sqrt[3]{125}\)
( 2x + 1 ) = 5
2x = 5 - 1
2x = 4
x = 4 : 2
x = 2
(2x+5) 3 = -125
=> 2x+5= -5
2x= -5 -5 = -10
x= -10:2= -5
Vậy x=-5
(2x+5)³ = -125
=> (2x+5)3 = (-5)3
=> 2x+5 = -5
=> 2x = -5-5
=> 2x = -10
=> x = (-10) : 2
=> x = -5
Vậy x = -5