Question

Số các giá trị nguyên x thỏa mãn \(3x\left(\left|x\right|-4\right)\left(x^2-81\right)=0\) là ???

help !!!!!!!!!

Answer 1

\(3x\left(\left|x\right|-4\right)\left(x^4-81\right)=0\)

\(\Rightarrow\left[\begin{matrix}3x=0\\\left|x\right|-4=0\\x^4-81=0\end{matrix}\right.\Rightarrow\left[\begin{matrix}x=0\\\left|x\right|=4\\x^4=81\end{matrix}\right.\Rightarrow\left[\begin{matrix}x=0\\x=\pm4\\x=\pm3\end{matrix}\right.\)

Vậy \(x\in\left\{0;4;-4;3;-3\right\}\)

Answer 2

\(3x\left(\left|x\right|-4\right)\left(x^2-81\right)=0\)

\(\Rightarrow\left[\begin{matrix}3x\left(\left|x\right|-4\right)=0\\x^2-81=0\end{matrix}\right.\Rightarrow\left[\begin{matrix}\left|x\right|-4=0\\x^2=81\end{matrix}\right.\Rightarrow\left[\begin{matrix}\left|x\right|=4\\x=\pm9\end{matrix}\right.\Rightarrow\left[\begin{matrix}x=\pm4\\x=\pm9\end{matrix}\right.\)

Vậy \(x\in\left\{4;-4;9;-9\right\}\)

Answer 3

á chết nhầm đề, thế này ms đúng nha

\(3x\left(\left|x\right|-4\right)\left(x^4-81\right)=0\)