Boularas, Driss2019-12-112019-12-112000-03-28Boularas, D. (2000). A note on the saddle conic of quadratic planar differential systems. <i>Electronic Journal of Differential Equations, 2000</i>(23), pp. 1-9.1072-6691https://hdl.handle.net/10877/9053We give some properties of the saddle conic of quadratic differential systems. We also deduce semi-algebraic conditions for the existence of one, two or three saddle points (in terms of affine invariants).Text9 pages1 file (.pdf)enAttribution 4.0 InternationalNonlinear differential systemsSaddle pointsQualitative theory of ordinary differential systemsCritical pointsInvariant theoryArticle