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25 tháng 9 2018

Ta có

\(x^{13}=x^{12}\)

\(\Rightarrow x^{13}-x^{12}=0\)

\(\Rightarrow x^{12}\left(x-1\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x^{12}=0\\x-1=0\end{cases}\Rightarrow\orbr{\begin{cases}x=0\\x=1\end{cases}}}\)

3 tháng 10 2016

a) Ta có 

x8=(x4)2=>n=4

23 tháng 7 2019

1, \(a,\left(x+1\right)^2=3\)

\(\Rightarrow x+1=\pm\sqrt{3}\)

\(\Rightarrow x=\pm\sqrt{3}-1\)

\(b,\left(x-1\right)^{x+2}=\left(x-1\right)^{x+6}\)

\(\Rightarrow\left(x-1\right)^{x+6}-\left(x-1\right)^{x+2}=0\)

\(\Rightarrow\left(x-1\right)^{x+2}\left[\left(x-1\right)^4-1\right]=0\)

\(\Rightarrow\orbr{\begin{cases}\left(x-1\right)^{x+2}=0\\\left(x-1\right)^4-1=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x-1=0\\\left(x-1\right)^4=1\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=1\\x-1=\pm1\Rightarrow x=2or\text{ }x=0\end{cases}}\)

\(c,\left(x+\frac{1}{2}\right)^2=\frac{4}{25}\)

\(\Rightarrow x+\frac{1}{2}=\pm\sqrt{\frac{4}{25}}\)

\(\Rightarrow x+\frac{1}{2}=\pm\frac{2}{5}\)

\(\Rightarrow\orbr{\begin{cases}x+\frac{1}{2}=\frac{2}{5}\\x+\frac{1}{2}=-\frac{2}{5}\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-\frac{1}{10}\\x=-\frac{9}{10}\end{cases}}\)

2, \(a,\sqrt{x}=4\)

\(\Rightarrow\sqrt{x}=\sqrt{16}\)

\(\Rightarrow x=16\)

\(b,\sqrt{x+1}=5\)

\(\Rightarrow\sqrt{x+1}=\sqrt{25}\)

\(\Rightarrow x+1=25\)

\(\Rightarrow x=24\)

\(\Rightarrow5^{\left(x+2\right)\left(x+3\right)}=1\)

\(\Rightarrow5^{\left(x+2\right)\left(x+3\right)}=5^0\)

\(\Rightarrow\left(x+2\right)\left(x+3\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x+2=0\\x+3=0\end{cases}\Rightarrow\orbr{\begin{cases}x=-2\\x=-3\end{cases}}}\)

\(d,\left(2x-1\right)^{12}=\left(x+1\right)^{12}\)

\(\Rightarrow\left(2x-1\right)^{12}\div\left(x+1\right)^{12}=1\)

\(\Rightarrow\) 

a: (x-3)2=49

=>x-3=7 hoặc x-3=-7

=>x=10 hoặc x=-4

b: \(\left(x^4\right)^2=\dfrac{x^{12}}{x^5}\)

\(\Leftrightarrow x^8-x^7=0\)

\(\Leftrightarrow x^7\left(x-1\right)=0\)

=>x=0 hoặc x=1

c: \(\Leftrightarrow x^{10}-25x^8=0\)

\(\Leftrightarrow x^8\left(x^2-25\right)=0\)

\(\Leftrightarrow x^8\left(x-5\right)\left(x+5\right)=0\)

hay \(x\in\left\{0;5;-5\right\}\)

23 tháng 6 2018

1,

\(\left(2x+1\right)^3=-0,001\\ \left(2x+1\right)^3=\left(-0.1\right)^3\\ \Leftrightarrow2x+1=-0.1\\ 2x=-1.1\\ x=-\dfrac{11}{10}:2\\ x=-\dfrac{11}{20}\\ Vậy...\)

2,

\(\left(2x-3\right)^4=\left(2x-3\right)^6\\ \Leftrightarrow\left(2x-3\right)^6-\left(2x-3\right)^4=0\\ \Leftrightarrow\left(2x-3\right)^4\cdot\left[\left(2x-3\right)^2-1\right]=0\\ \Rightarrow\left\{{}\begin{matrix}\left(2x-3\right)^4=0\\\left(2x-3\right)^2-1=0\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}2x-3=0\\\left(2x-3\right)^2=1\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}2x=3\\2x-3=1\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{3}{2}\\x=2\end{matrix}\right.\\ Vậyx\in\left\{\dfrac{3}{2};2\right\}\)

3, Làm tương tự câu 2

5,

\(9^x:3^x=3\\ \left(9:3\right)^x=3\\ 3^x=3\\ \Rightarrow x=1\\ Vậy...\)

6,

\(3^x+3^{x+3}=756\\ 3^x+3^x\cdot3^3\\ 3^x\cdot\left(1+27\right)=756\\ 3^x\cdot28=756\\ \Leftrightarrow3^x=27\\ 3^x=3^3\\ \Rightarrow x=3\\ vậy...\)

7,

\(5^{x+1}+6\cdot5^{x+1}=875\\ 5^{x+1}\cdot\left(1+6\right)=875\\ 5^{x+1}\cdot7=875\\ \Leftrightarrow5^{x+1}=125\\ \Leftrightarrow5^{x+1}=5^3\Leftrightarrow x+1=3\\ \Rightarrow x=2\\ Vậy...\)

9,

23 tháng 6 2018

lê thị hồng vân trả lời típ đikhocroi

26 tháng 8 2017

linhpham linh

\(\left(x+\frac{3}{4}\right)^2=\frac{49}{16}\)

\(\Rightarrow\left(x+\frac{3}{4}\right)^2=\frac{7^2}{4^2}\)

\(\Rightarrow\left(x+\frac{3}{4}\right)^2=\left(\frac{7}{4}\right)^2\)

\(\Rightarrow x+\frac{3}{4}=\frac{7}{4}\)

\(\Rightarrow x=\frac{7}{4}-\frac{3}{4}\)

\(\Rightarrow x=1\)

a) \(\left(x+\frac{3}{4}\right)^2=\frac{49}{16}\)

=> x + \(\frac{3}{4}=\frac{7}{4}\)

=> x = \(\frac{7}{4}-\frac{3}{4}=\frac{4}{4}=1\)

c) (3x - 1)2 = 81

=> 3x - 1 = 9

=> 3x = 10

=> x = \(\frac{10}{3}\)