Aparabola has a vertex at (0,0). the focus of the parabola is located on the positive y-axis. in which direction must the parabola open? up down left right

The parabola opens in the direction of the focus.

Since the focus is above the vertex, it opens up.

Given the vertex of (0,0) and the focus sitting above it on the y axis, we can assume the parabola will be opening up.  

In general, if given the focus a good way to remember the direction the parabola is the opening we can use the following phrase:  A parabola will "hug" the focus and "run away" from the directrix.  In other words, the parabola will wrap around the focus.  

Hope this is helpful.. let me know if you have questions.