If a=b= 1 and-1 < x < 1, the parabola has only one common point with the x axis.

3ax2+2bx+c=3x2+2x+c=0 There is only one real number solution c= 1/3.

If a+b+c=0 x 1=0, y 1 = c > 0x2 = 1, y2 = 3a+2 b+c>；; 0 a+b+c=0。

2a+b & gt； 0 and c>0 plus 2a+b+ c>；; 0 and a+b+c=0 minus a >；; 0

Upward parabolic opening a+b+c = 0 b

If the parabola and the X axis have a common point 3ax2+2bx+c=0, there is a real root △ = b 2-4ac > =0.

4b^2-4*3a*c>； =0 a+b+c=0 a+c=-b Let b=-2 and a= 1 c= 1 have two real roots.

So, there is one thing in common.