\(\frac{125}{\left(-5\right)^n}=-25\Rightarrow\left(-5\right)^n=\frac{125}{-25}=-5\)
\(\Rightarrow\left(-5\right)^n=\left(-5\right)^1\)
\(\Rightarrow n=1\)
a) \(\frac{125}{\left(-5\right)^n}=-25\)
⇒ \(\left(-5\right)^n=125:\left(-25\right)\)
⇒ \(\left(-5\right)^n=-5\)
⇒ \(\left(-5\right)^n=\left(-5\right)^1\)
⇒ \(n=1\)
Vậy \(n=1.\)
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