If the graph of f (x)=ax2+bx+c then how do we know the value of b from the graph. We will come to know the value of a & c by the shape of the graph like open upward or downward but what about 'b' explain

Answer 1

http://jwilson.coe.uga.edu/EMAT6680Su08/Henderson/Assignment3.html

Notice how the vertex shifts, and the parabola opens.