How do you graph a quadratic function?

Step-by-step explanation:

Compare the equation with the standard form, y=ax2+bx+c . Since the value of a is positive, the parabola opens up.

So, y=0 implies, by the zero product property, x+4=0 or x−2=0 .

Substitute x=−1 in the equation y=−x2−2x+8 to find the y -coordinate of the vertex.