a) \(x^3-5x^2+x-5=0\)
\(\Leftrightarrow\left(x-5\right)\left(x^2+1\right)=0\)
Vì \(x^2+1>0\)
\(\Rightarrow x-5=0\)
\(\Rightarrow x=5\)
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b) Mình nghĩ là sai đề nên sửa lại nhé :
\(x^4-2x^3+10x^2-20x=0\)
\(\Leftrightarrow\) \(x^3\left(x-2\right)+10x\left(x-2\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(x^3+10x\right)=0\)
\(\Leftrightarrow\left(x-2\right)x\left(x^2+10\right)=0\)
Vì \(x^2+10>0\)
\(\Rightarrow\left\{{}\begin{matrix}x=0\\x-2=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=0\\x=2\end{matrix}\right.\)
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