Question 460473: Good moprning everyone,
This is my question:
How do you graph a parabola. How do you know if the parabola opens upward or downward.
Thank you
Gina
Answer by josmiceli(19441)   (Show Source):
You can put this solution on YOUR website! The 1st step would be to find the axis of symmetry.
This would be a vertical line,  . The parabola
is symmetrical to the left and right of this line.
If the equation is expressed as  , then
 .
The base, or the point with zero slope, will be  .
Plug the value of  back into the equation to get 
If  is positive, the parabola opens up.
If is negative, it opens down.
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Here's an example:
is negative, so it opens down.
 is the axis of symmetry
Plugging this back in:
So, the base point is (3/4, -11)
The parabola can touch the x-axis in
1 point, 2 points, or no points.
Here's a plot:
The y-intercept is at  , so
 , so you have the point (0, -12)
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