Four Roots on a Circle

Problem

The real-coefficient equations

x2−2x+2=0andx2+2mx+1=0x^2 - 2x + 2 = 0 \qquad\text{and}\qquad x^2 + 2mx + 1 = 0

have four distinct roots whose points in the complex plane are concyclic. Find the range of mm.

Answer

Solution

Difficulty7/10
Topicscomplex numbers, Quadratic Equations, Circles, Casework

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