\(4^x+4^{x+3}=2160\)
\(4^x\left(1+4^3\right)=2160\)
\(4^x\cdot65=2160\)
\(4^x=2160\text{ : }65\)
\(4^x=33,2307692\)
\(\Rightarrow\text{ Đề sai}\)
Bài giải
\(2^{x-1}+5\cdot2^{x-2}=\frac{7}{32}\)
\(2^{x-2}\left(2+5\cdot1\right)=\frac{7}{32}\)
\(2^{x-2}\cdot7=\frac{7}{32}\)
\(2^{x-2}=\frac{7}{32}\text{ : }7\)
\(2^{x-2}=32\)
\(2^{x-2}=2^5\)
\(\Rightarrow\text{ }x-2=5\)
\(x=5+2\)
\(x=7\)