^表示次方b^2x^2+(b^2+c^2-a^2)x-c^2=0(bx+(b^2+c^2-a^2)/(2b))^2=c^2+((b^2+c^2-a^2)/(2b))^2要有实数解,则：c^2+((b^2+c^2-a^2)/(2b))^2>=0c^2+(b^4+c^4+a^4+2(bc)^2-2(ac)^2-2(bc)^2)/(4b^2)>=0不好意思,写起来太...