a) |x-3|=5
\(\Rightarrow\left[{}\begin{matrix}x-3=-5\\x-3=5\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=-2\\x=8\end{matrix}\right.\)
Vậy x\(\in\){-2;8}
b) (x+2)2=81
(x+2)2=92
\(\Rightarrow\)x+2=9
x=9-2
x=7
Vậy x=7.
c) 5x+5x+2=650
5x+5x.52=650
5x(1+52)=650
5x.26=650
5x=650:26
5x=25
5x=52
\(\Rightarrow\)x=2
Vậy x=2.
a) \(\left|x-3\right|=5\\ \Rightarrow\left[{}\begin{matrix}x-3=5\\x-3=-5\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=8\\x=-2\end{matrix}\right.\)Vậy \(x\in\left\{8;-2\right\}\)
b) \(\left(x+2\right)^2=81\\ \left(x+2\right)^2=9^2=\left(-9\right)^2\\ \Rightarrow\left[{}\begin{matrix}x+2=9\\x+2=-9\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=7\\x=-11\end{matrix}\right.\)Vậy \(x\in\left\{7;-11\right\}\)
c) \(5^x+5^{x+2}=650\\ 5^x\left(1+5^2\right)=650\\ 5^x\cdot26=650\\ 5^x=25\\ \Rightarrow x=2\)Vậy x = 2
\( a)\left| {x - 3} \right| = 5\\ \Leftrightarrow \left[ \begin{array}{l} x - 3 = 5\\ x - 3 = - 5 \end{array} \right. \Leftrightarrow \left[ \begin{array}{l} x = 8\\ x = - 2 \end{array} \right.\\ b){\left( {x + 2} \right)^2} = 81\\ \Leftrightarrow x + 2 = \pm 9\\ \Leftrightarrow \left[ \begin{array}{l} x + 2 = 9\\ x + 2 = - 9 \end{array} \right. \Leftrightarrow \left[ \begin{array}{l} x = 7\\ x = - 11 \end{array} \right.\\ c){5^x} + {5^{x + 2}} = 650\\ \Leftrightarrow \left( {1 + {5^2}} \right){5^x} = 650\\ \Leftrightarrow {26.5^x} = 650\\ \Leftrightarrow {5^x} = 25\\ \Leftrightarrow {5^x} = {5^2}\\ \Leftrightarrow x = 2 \)
