How this calculation works
Find the constant that makes a quadratic touch the x-axis at its vertex.
THE FORMULA
A repeated root requires b²−4ac=0, so c=b²/(4a)A worked example
2x²+8x+8 has a repeated root at −2.
Good to know
The leading coefficient cannot be zero.
Reference: OpenStax Algebra and Trigonometry (opens in a new tab) ↗
Read the result
Find the constant that makes a quadratic touch the x-axis at its vertex.
The primary result is labeled “Required constant c”. Keep the input definitions in view when comparing this result with another method.
Try a related calculation
The leading coefficient cannot be zero.
For a related exercise, try the quadratic equation solver.
A few questions, answered
How can I check the default inputs by hand?
2x²+8x+8 has a repeated root at −2.
Which rule does this calculator apply?
A repeated root requires b²−4ac=0, so c=b²/(4a)