a)
\(\frac{16}{2^x}=2\)
\(\Rightarrow2^{x+1}=16\)
\(\Rightarrow2^{x+1}=2^4\)
\(\Rightarrow x+1=4\)
\(\Rightarrow x=3\)
b)
\(\frac{\left(-3\right)^x}{81}=-27\)
\(\Rightarrow\left(-3\right)^x=-\left(3^3.3^4\right)\)
\(\Rightarrow-3^x=-3^7\)
=> x=7
c)
\(8^n:2^n=4\)
\(\Rightarrow2^{3n}:2^n=4\)
\(\Rightarrow2^{3n-n}=4\)
\(\Rightarrow2^{2n}=2^2\)
=>2n=2
=>n=1
a) \(\frac{16}{2^n}=2\Rightarrow2^nx2=16\)
\(\Rightarrow2^n=16:2=8=2^3\)
\(\Rightarrow n=3\)
b) \(\frac{\left(-3\right)^n}{81}=-27\Rightarrow\left(-3\right)^n=\left(-27\right)x81=-2187\)
\(\Rightarrow\left(-3\right)^n=\left(-3\right)^7\Rightarrow n=7\)
c) \(8^n:2^n=4\Rightarrow\left(2^3\right)^n:2^n=2^2\)
\(\Rightarrow2^{3n}:2^n=2^2\)
\(\Rightarrow3n-n=2\)
\(\Rightarrow2n=2\Rightarrow n=1\)
Chúc bạn học tốt!
