Question

\(\left(-3\right)^{x+5}=\frac{1}{81}\)

Answer 1

\(\left(-3\right)^{x+5}=\frac{1}{81}\)

\(\left(-3\right)^{x+5}=\left(-3\right)^{-4}\)

\(=>x+5=-4\)

\(=>x=-4-5\)

\(=>x=-9\)

Answer 2

\(\left(-3\right)^{x+5}=\frac{1}{81}\)

\(\Rightarrow\left(-3\right)^{x+5}=\left(-3\right)^{-4}\)

\(\Rightarrow x+5=-4\)

\(\Rightarrow x=-4-5\)

\(\Rightarrow x=-9\)

Answer 3

Ta có : 

\(\left(-3\right)^{-4}=\frac{1}{81}\)

Nên 

\(\left(-3\right)^{x+5}=\left(-3\right)^{-4}\)

\(\Rightarrow x+5=-4\)

\(\Rightarrow x=-4-5\)

\(\Rightarrow x=-9\)

Vậy \(x=-9\)