There are two equations for a parabola. y = a( x - h )^2 + kandx = a( y - k )^2 + hThe (h, k) are the (x, y) coordinates for the vertex on the parabola -- the point where the parabola starts.You can visualize the graph for these parabolas by looking at the y = and x = part of the equation. For the y= part of the equation you can see if y is equal to a positive number then the graph will go up. If y were equal to a negative number then it would go down. Because a square is always positive it is easy to see the only variable that could ever make y negative is the variable 'a' if y is positive then the parabola opens up and if y is negative the parabola opens downward.The same is true for the other equation (x = ) if x is positive then the parabola is graphed to the right (as x increases in value) and if x is negative then the parabola is graphed to the LEFT.