# Lill's Construction for a Depressed Cubic Polynomial

Requires a Wolfram Notebook System

Interact on desktop, mobile and cloud with the free Wolfram CDF Player or other Wolfram Language products.

Requires a Wolfram Notebook System

Edit on desktop, mobile and cloud with any Wolfram Language product.

This Demonstration shows a graphic check of Lill's construction of a polynomial of the form where .

[more]
Contributed by: Izidor Hafner (September 2017)

Open content licensed under CC BY-NC-SA

## Snapshots

## Details

Since we are mainly interested in zeros of the polynomial , it looks like this Demonstration is less general than the so-called depressed equation . But Vieta showed that in the irreducible case, using the substitution gives the equation [2, p. 133].

References

[1] D. Kurepa, *Higher Algebra, Book 2* (in Croatian), Zagreb: Skolska knjiga, 1965 pp. 1072–1074.

[2] G. E. Martin, *Geometric Constructions*, New York: Springer, 1998.

## Permanent Citation