f(x)=(3x^2+x+1)/(2x^2-x+1),
f(x)=y,
y=(3x^2+x+1)/(2x^2-x+1),
y(2x^2-x+1)=3x^2+x+1,
2yx^2-yx+y=3x^2+x+1,
(2y-3)x^2-(y+1)x+y-1=0,
D=(y+1)^2-4(2y-3)(y-1)=y^2+2y+1-8y^2+8y+12y-12=-7y^2+22y-11,
D>=0, -7y^2+22y-11>=0,
7y^2-22y+11<=0,</p>
7y^2-22y+11=0,
D/4=44,
y_1=(11-2√11)/7≈0,6,
y_2=(11+2√11)/7≈2,5.
(11-2√11)/7≤y≤(11+2√11)/7,
Ey=[(11-2√11)/7;(11+2√11)/7].