If figure shows the graph of f(x)=ax2+bx+c, then

From the graph,  f(0)=c>0                   (1)Also, the graph is concave downward. Hence,         a<0                   (2)Further, abscissa of the vertex,        b2a<0                     (3)From (1), (2), (3),ac<0,ab<0 and bc>0