\(6x^2+\left(2y-1\right)x+10y^2-28y+18=0\)
\(\Delta=\left(2y-1\right)^2-24\left(10y^2-28y+18\right)\ge0\)
\(\Leftrightarrow-236y^2+668y-431\ge0\)
\(\Rightarrow\dfrac{167-2\sqrt{615}}{118}\le y\le\dfrac{167+2\sqrt{615}}{118}\)
\(\Rightarrow y=1\)
Thế vào pt đầu ...