Quadratic formulas for quaternions
Let \(\mathbb{R}\) denote the field of real numbers and \(\mathbb{H}\) denote the algebra of real quaternions. The authors of the paper provide the explicit formulas for computing all roots of a quadratic polynomial of the form \(x^2+bx+c\), for all \(b,c\in \mathbb{H}\). The general situation is divided into several particular cases depending on the relations between parameters \(b\) and \(c\). In each case the direct expressions of all roots through the parameters \(b\) and \(c\) are derived. As a corollary, the necessary and sufficient conditions on parameters \(b,c\) that guarantee the existence of exactly one, two, or infinitely many different roots are given. The results of this paper unify several particular results on this subject [see, \textit{S. Zhang} and \textit{D. Mu}, J. Math. Res. Expo. 14, No. 2, 260-264 (1994; Zbl 0815.16007), \textit{R. M. Porter}, J. Nat. Geom. 11, No. 2, 101-106 (1997; Zbl 0869.11024), \textit{I. Niven}, Am. Math. Mon. 48, 654-661 (1941; Zbl 0060.08002)].
scientific article; zbMATH DE number 1781915