a) \(5^x+5^{x+2}=650\)
\(\Leftrightarrow5^x+5^x.5^2=650\)
\(\Leftrightarrow5^x\left(1+5^2\right)=650\)
\(\Leftrightarrow5^x.26=650\)
\(\Leftrightarrow5^x=25\)
\(\Leftrightarrow5^x=5^2\)
\(\Leftrightarrow x=2\left(tm\right)\)
Vậy .................
b) \(3^{x-1}+5.3^{x-1}=162\)
\(\Leftrightarrow3^{x-1}\left(5+1\right)=162\)
\(\Leftrightarrow3^{x-1}.5=162\)
\(\Leftrightarrow3^{x-1}=27\)
\(\Leftrightarrow3^{x-1}=3^3\)
\(\Leftrightarrow x-1=3\)
\(\Leftrightarrow x=2\left(tm\right)\)
Vậy ...................
\(5^x+5^{x+2}=650\)
\(\Rightarrow5^x.1+5^x.5^2=650\)
\(\Rightarrow5^x\left(1+5^2\right)=650\)
\(\Rightarrow5^x.26=650\)
\(\Rightarrow5^x=25\)
\(\Rightarrow x=2\)
Tương tự
a) \(5^x+5^{x+2}=650\)
\(\Rightarrow5^x+5^x.5^2=650\)
\(\Rightarrow5^x\left(1+5^2\right)=650\)
\(\Rightarrow5^x=\dfrac{650}{26}=25\)
\(\Rightarrow5^x=5^2\)
\(\Rightarrow x=2\)
b) \(3^{x-1}.5.3^{x-1}=162\)
\(3^x.\dfrac{1}{3}.5.3^x.\dfrac{1}{3}=162\)
\(3^{2x}.\dfrac{1}{9}.5=162\)
\(3^{2x}=162:\dfrac{5}{9}\)
\(9^x=\dfrac{1458}{5}\)
Hình như có j đó sai sai ở đây.....
