Question

Tìm STN n biết: 

n³ = n⁵

Answer 1

Có : \(1^3=1^5\) 

\(\Rightarrow\) Số tự nhiên \(n\) là \(1\)

Answer 2

\(n^3=n^5\)

\(\Rightarrow n^5-n^3=0\)

\(\Rightarrow n^3\left(n^2-1\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}n^3=0\\n^2-1=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}n=0\\\left[{}\begin{matrix}n=1\\n=-1\end{matrix}\right.\end{matrix}\right.\)

Mà \(n\in N\Rightarrow n=\left\{0;1\right\}\)