The equation below describes a parabola. if a is positive, which way does the parabola open? x = ay2

One of the best way to solve these kinds of questions is to draw 3-4 points and than conclude from that how graph will go.

Because this function is f(y) (x depends on y) you randomly take several y values and calculate x for them and those are your pairs of coordinates of several points.

y = 0
x = 0

y = 1
x = a

y = -1
x = a

y = 2
x = 4a

y = -2
x = 4a

So if you draw these points on graph you will see it opens in positive direction of x axis.