Grade 11 · Mathematics
Vertex form
Why it matters
Graphing parabolas.
Core20m readingPrerequisite: None
What is the vertex form of a quadratic function?
Short answer
Vertex form writes a quadratic as y = a(x − h)² + k, where (h, k) is the vertex of the parabola and a controls its width and direction. If a is positive the parabola opens up (minimum at the vertex); if negative it opens down (maximum). Vertex form makes graphing and finding the maximum or minimum immediate.
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Frequently asked questions
- What does the vertex tell you?
- It is the highest or lowest point of the parabola — the maximum if it opens down, the minimum if it opens up.
- How do you convert standard form to vertex form?
- By completing the square on the quadratic and linear terms.