2X方+3X-4 =5除以2X方+3x2x^2+3x-4=5/(2x^2+3x)设y=2x^2+3x ,那么,y-4=5/yy^2-4y-5=0(y-5)(y+1)=0y1=5 y2=-12x^2+3x=5 2x^2+3x=-1(x-1)(2x+5)=0 (x+1)(2x+1)=0x1=1 x2=-5/2 x3=-1 x4=-1/2