So to answer your question I will first define what the axis of symmetry is:
<em> The axis of symmetry of a parabola is a vertical line that divides the parabola into 2 halves </em>like my graph shown below. The graph of a quadratic function is known as a parabola.
Thus it is as simple as graphing the equation and finding the lowest point <em>(aka: the vertex)</em>.
The answer to this question is
If you have anymore questions don't be afraid to ask, <em>I'm here to help</em>. Thanks!