How to use this calculator

Zeros are inputs where a function evaluates to zero. On a graph they correspond to x-axis crossings or touches. This tool accepts a polynomial coefficient list, isolates real roots using derivative information, and reports a substitution residual for each numerical result.

The method

Find x such that f(x) = 0

Enter the values in the labeled fields, check the units or selected mode, and choose Calculate. The result includes the applicable working and a breakdown or visual when useful. Change an input and calculate again to update the result.

WORKED EXAMPLE

Polynomial coefficients: 1, -6, 11, -6

Zeros of the polynomial: 1, 2, 3

f(x) = x^3 - 6x^2 + 11x - 6

Scope and limitations

Polynomials only, through degree 6. Complex roots are returned for quadratics only. Numerical root finding can be sensitive to nearly repeated roots and poorly scaled coefficients; verify critical results independently.

Common questions

Can it find a root where the graph only touches the axis?

The solver also checks derivative critical points, allowing many repeated roots to be detected without a sign change.

Can I enter sin(x) or log(x)?

No. This version accepts polynomial coefficients. Dedicated trigonometric and logarithmic graphing tools are available.

References & further reading

External references provide background, not an endorsement of this implementation. See our methodology for numerical conventions and limitations.