For a parabola in standard form (y=ax^2+bx+c), use (x=-frac{b}{2a})
For a parabola in vertex form (y=a(x-h)^2+k), use (x=h)
For a parabola in factored form (y=a(x-r_1)(x-r_2)), use (x=frac{r_1+r_2}{2})
For a graph, find the vertical line that passes through the vertex
For two x-intercepts, find the midpoint between them
For a table of values, find the x-value where the y-values on both sides match
For a symmetric graph, identify the line that divides it into two mirror-image halves