Question

Tìm x, biết: (5-x).(9x^2-4)=0

Answer 1

\(\left(5-x\right)\left(9x^2-4\right)=0\)

=>\(\left(x-5\right)\left(3x-2\right)\left(3x+2\right)=0\)

=>\(\left[{}\begin{matrix}x-5=0\\3x-2=0\\3x+2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5\\x=\dfrac{2}{3}\\x=-\dfrac{2}{3}\end{matrix}\right.\)

Answer 2

\(\left(5-x\right)\left(9x^2-4\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}5-x=0\\9x^2-4=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=5\\x^2=\dfrac{4}{9}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=5\\x=\dfrac{2}{3}\\x=-\dfrac{2}{3}\end{matrix}\right.\)