\(\Rightarrow\left[{}\begin{matrix}2x=\dfrac{3}{7}\\2x^2=-18\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{3}{14}\\x^2=-9\left(voly\right)\end{matrix}\right.\)
\(\Rightarrow x=\dfrac{3}{14}\)
\(=>\left[{}\begin{matrix}2x-\dfrac{3}{7}=0\\2x^2+18=0\left(\ge0\forall x\right)\end{matrix}\right.\\ =>2x-\dfrac{3}{7}=0\\ =>2x=\dfrac{3}{7}\\ =>x=\dfrac{3}{7}:2=\dfrac{3}{14}\)
\(=>\left[{}\begin{matrix}2x-\dfrac{3}{7}=0\\2x^2+18=0\end{matrix}\right.< =>\left[{}\begin{matrix}2x=\dfrac{3}{7}\\2x^2=-18\end{matrix}\right.< =>\left[{}\begin{matrix}x=\dfrac{3}{14}\\x=\varnothing\end{matrix}\right.\)
\(\left(2x-\dfrac{3}{7}\right)\left(2x^2+18\right)=0\)
\(\Rightarrow\left\{{}\begin{matrix}2x-\dfrac{3}{7}=0\\2x^2+18=0\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{3}{14}\\x=\varnothing\end{matrix}\right.\)
tại x = 18; y = 4 
