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Quadratic Vertex Calculator

Find the vertex coordinates of y = ax² + bx + c and identify the extremum from the leading coefficient.

Enter your values

Enter a numeric value.
Enter a numeric value.
Enter a numeric value.

Use a decimal point, without thousands separators.

Example result
Vertex x-coordinate h
3
Vertex y-coordinate k-4

The initial result uses the example values. Enter your own values and calculate again.

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How it works

The vertex is the point (h, k) on the axis x = h. For y = x² − 6x + 5, h = 3 and k = −4. Positive a gives a minimum; negative a gives a maximum. This calculation finds the turning point rather than the roots where the parabola meets y = 0.

Inputs and units
Quadratic Vertex Calculator · Inputs and units
InputExample valueWhat to enter
Coefficient a1Enter a numeric value.
Coefficient b-6Enter a numeric value.
Constant c5Enter a numeric value.
h = −b/(2a); k = ah² + bh + c

Worked example

Show example inputs and results

This example is generated by the same calculation engine using the starting values in the form. Your own inputs produce your own result.

Coefficient a
1
Coefficient b
-6
Constant c
5

Complete example results

Vertex x-coordinate h
3
Vertex y-coordinate k
-4

Reading the result

Use quantities on the same basis. The starting value in percentage change, the denominator in a ratio and the length unit in geometry determine the meaning of the answer. Check the formula conditions alongside the example.

Questions and answers

Can I use the example values for my own calculation?

The example values illustrate the calculation. Replace every input with your own information, especially dates, rates and the selected operation.

Why is a = 0 rejected?

With a = 0 the expression is linear or constant and is not a parabola with one quadratic turning point.

Why are some results rounded?

Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.

Are my inputs sent to a server?

The calculator processes inputs in your browser. Its code does not send your values to a server.

Methods & accuracy

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