\(\hept{\begin{cases}4x-y=5\left(1\right)\\16y^2-8xy+x^2-40xy+10x+25=0\left(2\right)\end{cases}}\)
(1) thay (2) => \(\left(4x-5\right)^2-8x\left(4x-5\right)^2+x^2-40x\left(4x-5\right)+10x+25=0\)
\(\Leftrightarrow16x^2-40x+25-32x^2+40x+x^2-160x^2+200x+10x+25=0\)
\(\Leftrightarrow-175x^2+210x+50=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=\frac{21+\sqrt{791}}{35}\Rightarrow y=\frac{-91+4\sqrt{791}}{35}\\x=\frac{21-\sqrt{791}}{35}\Rightarrow y=-\frac{91+4\sqrt{791}}{35}\end{cases}}\)