Vertex of a Parabola Calculator
𝑥 Algebra. Use the Vertex of a parabola formula to find vertex x, a, b: pick the value you want, type the others, and the answer updates as you go.
The x of the turning point of y = ax² + bx + c (also its line of symmetry).
Vertex x2.5
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| Vertex x | no unit |
| a | no unit |
| b | no unit |
Worked example
Find the vertex x when a = 1, b = -5.
Using xv = -b/2a: Vertex x = 2.5.
Frequently asked questions
What is the formula for Vertex of a parabola?
xv = -b/2a. The x of the turning point of y = ax² + bx + c (also its line of symmetry).
What do the letters stand for, and what units are used?
Vertex x, a, b.
How do you calculate vertex x?
Put the values into xv = -b/2a. For example, with a = 1, b = -5, vertex x = 2.5.
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (vertex x, a, b) and fill in the others: it rearranges the formula for you.
