Question

tìm x 

x mũ 3 - 9/16 . x = 0

Answer 1

`x^3 -9/16 .x=0`

`x. (x^2 -9/16)=0`

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

Vậy `x=0 ; x=3/4 ;x=-3/4`.

Answer 2

\(x^3-\dfrac{9}{16}.x=0\) 

\(x.\left(x^2-\dfrac{9}{16}\right)=0\) 

\(\Rightarrow\left[{}\begin{matrix}x=0\\x^2-\dfrac{9}{16}=0\end{matrix}\right.\) 

\(\Rightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{3}{4};x=\dfrac{-3}{4}\end{matrix}\right.\)