ax^2+bx+c>0的解集为-1/3则-1/3和2是对应方程ax^2+bx+c=0的根所以-1/3+2=-b/a-1/3*2=c/ab=(-5/3)ac=(-2/3)a所以b/c=5/2a/c=-3/2ax^2+bx+c>0大于0而解集为-1/3则ax^2+bx+c>0两边除以a有变成了x^2+(b/a)x+(c/a)<0所以a<0a/c<0所以c>0cx^2+bx+a<0x^2+(b/c)x+(a/c)<0x^2+(5/2)x+(3/2)=0(x+1)(x+3/2)<0-3/2
