(3x^2+4x+7)/(x^2-3x+4)<1
(3x^2+4x+7)/(x^2-3x+4)-1<0
(3x^2+4x+7-(x^2-3x+4))/(x^2-3x+4)<0
(3x^2+4x+7-x^2+3x-4)/(x^2-3x+4)<0
(2x^2+7x+3)/(x^2-3x+4)<0
(2x+1)(x+3)/(x^2-3x+4)<0
对x^2-3x+4而言,因为△=(-3)^2-4*4=9-16=-7<0
所以 x^2-3x+4总是大于0
则 -3