Question

Tìm x:

\(9x^3-16x=0\)

Answer 1

\(9x^3-16x=0\\ x\left(9x^2-16\right)=0\\ x\left[\left(3x\right)^2-4^2\right]=0\\ x\left(3x-4\right)\left(3x+4\right)=0\\ ⇒\:\left[{}\begin{matrix}x=0\\3x-4=0\\3x+4=0\end{matrix}\right.⇒\:\left[{}\begin{matrix}x=0\\x=\dfrac{4}{3}\\x=-\dfrac{4}{3}\end{matrix}\right.\)

vậy \(x\in\left\{0;\pm\dfrac{4}{3}\right\}\)