Question

Phân tích đa thức thành nhân tử: x³ = 9x

Answer 1

\(x^3=9x\\ =>x^3-9x=0\\ =>x\left(x^2-9\right)=0\\ =>x\left(x-3\right)\left(x+3\right)=0\\ =>\left[{}\begin{matrix}x=0\\x+3=0\\x-3=0\end{matrix}\right.=>\left[{}\begin{matrix}x=0\\x=-3\\x=3\end{matrix}\right.\)

Answer 2

\(\Leftrightarrow x\left(x-3\right) \left(x+3\right)=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-3\\x=3\end{matrix}\right.\)

Answer 3

\(x^3=9x\)

\(<=>x^3+9x=0\)

\(<=>x(x^2+9)=0\)

\(<=>x(x^2+3^2)=0\)

\(<=>x(x+3)(x-3)=0\)

\(<=>[x=0<=>[x=0\)

\(<=>[x+3=0<=>[x=-3\)

\(<=>[x-3=0<=>[x=3\)

Answer 4

x ³  -  9x
= x (x² - 9)
= x (x² - 3²)
= x (x - 3) (x + 3)