What Is Vertex Form?
Vertex form writes a quadratic equation as y = a(x − h)² + k, where (h, k) is the vertex (the parabola's highest or lowest point) and a controls how wide or narrow it opens. It's the easiest form to graph from directly, since the vertex is visible without any extra calculation.
Example
y = 2(x − 3)² + 1 has its vertex at (3, 1). At x = 3, the squared term becomes 0, leaving y = 1, the parabola's minimum value since a = 2 is positive.