Question

Tìm x

\(4^{x+3}-3\cdot4^{x+1}=13\cdot4^{11}\)

Answer 1

\(4^{x+3}-3.4^{x+1}=13.4^{11}\)

\(\Rightarrow4^x.4^3-3.4^x.4=13.4^{11}\)

\(\Rightarrow4^x\left(4^3-3.4\right)=4^{11}.13\)

\(\Rightarrow4^x.52=4^{11}.13\)

\(\Rightarrow4^{x+1}.13=4^{11}.13\)

\(\Rightarrow x+1=11\)

\(\Rightarrow x=10\)

Answer 2

\(\Rightarrow4^{x+1}\left(4^2-3\right)-13.4^{11}=0\)

\(\Rightarrow13.4^{x+1}-13.4^{11}=0\)

\(\Rightarrow13.\left(4^{x+1}-4^{11}\right)=0\)

\(\Rightarrow4^{x+1}-4^{11}=0\)

\(\Rightarrow4^{x+1}=4^{11}\Rightarrow x+1=11\Rightarrow x=10\)