Question

tìm x thuộc n, biết

x mũ 20=x

Answer 1

\(x^{20}=x\)

⇒\(x^{20}-x=0\)

⇒\(x\left(x^{19}-1\right)=0\)

⇔\(x^{19}-1=0\) hoặc x=0

⇔x=1 hoặc x=0

Answer 2

\(x^{20}=x\\ \Leftrightarrow x^{20}-x=0\\ \Leftrightarrow x\left(x^{19}-1\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=1\end{matrix}\right.\)

Answer 3

\(x^{20}=x\\ \Rightarrow x\in\left\{0;1\right\}\)vì \(x\in N\)