Question

Tìm x , biết :

4^x + 4^{x + 3} = 4160

Answer 1

\(4^x+4^{x+3}=4160\)

\(4^x\times\left(1+4^3\right)=4160\)

\(4^x\times\left(1+64\right)=4160\)

\(4^x\times65=4160\)

\(4^x=\frac{4160}{65}\)

\(4^x=64\)

\(4^x=4^3\)

\(x=3\)

Answer 2

\(4^x+4^{x+3}=4160\)

\(\Rightarrow4^x+4^x.4^3=4160\)

\(\Rightarrow4^x.\left(1+4^3\right)=4160\)

\(\Rightarrow4^x.65=4160\)

\(\Rightarrow4^x=64\)

\(\Rightarrow4^x=4^3\)

\(\Rightarrow x=3\)

Vậy \(x=3\)