In mathematics, a cubic plane curve is a plane algebraic curve C defined by a cubic equation applied to homogeneous coordinates for the projective plane; or the inhomogeneous version for the affine space determined by setting z = 1 in such an equation. Here F is a non-zero linear combination of the third-degree monomials These are ten in number; therefore the cubic curves form a projective space of dimension 9, over any given field K. Each point P imposes a single linear condition on F, if we ask that C pass through P. Therefore, we can find some cubic curve through any nine given points, which may be degenerate, and may not be unique, but will be unique and non-degenerate if the points are in general position; compare to two points determining a line and how five points determine a conic. If two cubics pass through a given set of nine points, then in fact a pencil of cubics does, and the points satisfy additional properties; see Cayley–Bacharach theorem. A cubic curve may have a singular point, in which case it has a parametrization in terms of a projective line. Otherwise a non-singular cubic curve is known to have nine points of inflection, over an algebraically closed field such as the complex numbers. This can be shown by taking the homogeneous version of the Hessian matrix, which defines again a cubic, and intersecting it with C; the intersections are then counted by Bézout's theorem. However, only three of these points may be real, so that the others cannot be seen in the real projective plane by drawing the curve. The nine inflection points of a non-singular cubic have the property that every line passing through two of them contains exactly three inflection points. The real points of cubic curves were studied by Isaac Newton. The real points of a non-singular projective cubic fall into one or two 'ovals'. One of these ovals crosses every real projective line, and thus is never bounded when the cubic is drawn in the Euclidean plane; it appears as one or three infinite branches, containing the three real inflection points. The other oval, if it exists, does not contain any real inflection point and appears either as an oval or as two infinite branches. Like for conic sections, a line cuts this oval at, at most, two points. A non-singular plane cubic defines an elliptic curve, over any field K for which it has a point defined. Elliptic curves are now normally studied in some variant of Weierstrass's elliptic functions, defining a quadratic extension of the field of rational functions made by extracting the square root of a cubic. This does depend on having a K-rational point, which serves as the point at infinity in Weierstrass form. There are many cubic curves that have no such point, for example when K is the rational number field. The singular points of an irreducible plane cubic curve are quite limited: one double point, or one cusp. A reducible plane cubic curve is either a conic and a line or three lines, and accordingly have two double points or a tacnode (if a conic and a line), or up to three double points or a single triple point (concurrent lines) if three lines. (Wikipedia).
Algebraic geometry 2 Two cubic curves.
This lecture is part of an online algebraic geometry course, based on chapter I of "Algebraic geometry" by Hartshorne. It discusses two examples of cubic curves: a nodal cubic, and an elliptic curve.
From playlist Algebraic geometry I: Varieties
algebraic geometry 27 The twisted cubic
This lecture is part of an online algebraic geometry course, based on chapter I of "Algebraic geometry" by Hartshorne. It describes two examples: the twisted cubic is isomorphic to a projective line, and the affine plane without the origin is not isomorphic to any affine algebraic set.
From playlist Algebraic geometry I: Varieties
Cubic Curves (2 of 4: Polynomial Division & the factors of a Polynomial)
More resources available at www.misterwootube.com
From playlist Further Polynomials
Solving a Cubic Equation Using a Triangle
There is this surprising fact about cubic equations with 3 real solutions where an equilateral triangle centered on the inflection point can always be scaled/rotated by some amount such that its vertices will line up with the roots of the equation. But is there any way that this can be us
From playlist Summer of Math Exposition Youtube Videos
This video defines a cylindrical surface and explains how to graph a cylindrical surface. http://mathispower4u.yolasite.com/
From playlist Quadric, Surfaces, Cylindrical Coordinates and Spherical Coordinates
Maxima and Minima for Quadratic and Cubics | Algebraic Calculus One | Wild Egg
Tangents of algebraic curves are best defined purely algebraically, without recourse to limiting arguments! We apply our techniques for finding such tangents to derive some familiar results for quadratic and cubic polynomial functions and their maxima and minima. We compare also with the c
From playlist Algebraic Calculus One
algebraic geometry 33 Rationality of cubic surfaces
This lecture is part of an online algebraic geometry course, based on chapter I of "Algebraic geometry" by Hartshorne. It gives two rather informal and incomplete arguments for why nonsingular cubic surfaces are rational.
From playlist Algebraic geometry I: Varieties
What are Cubic Graphs? | Graph Theory
What are cubic graphs? We go over this bit of graph theory in today's math lesson! Recall that a regular graph is a graph in which all vertices have the same degree. The degree of a vertex v is the number of edges incident to v, or equivalently the number of vertices adjacent to v. If ever
From playlist Graph Theory
Christian Lehn: Symplectic varieties from cubic fourfolds
I will explain a construction of a family of 8-dimensional projective complex symplectic manifolds starting from the moduli space of twisted cubics on a general cubic fourfold. The relation to \mathrm{Hilb}^4 of a K3-surface is still open. This is a joint work with Manfred Lehn, Christoph
From playlist HIM Lectures: Junior Trimester Program "Algebraic Geometry"
Residual Intersections in Geometry and Algebra by David Eisenbud
DISTINGUISHED LECTURES RESIDUAL INTERSECTIONS IN GEOMETRY AND ALGEBRA SPEAKER: David Eisenbud (Director, Mathematical Sciences Research Institute, and Professor of Mathematics, UC Berkeley) DATE: 13 December 2019, 16:00 to 17:00 VENUE: Madhava Lecture Hall, ICTS-TIFR, Bengaluru In thi
From playlist DISTINGUISHED LECTURES
Elliptic curves: point at infinity in the projective plane
This video depicts point addition and doubling on elliptic curve in simple Weierstrass form in the projective plane depicted using stereographic projection where the point at infinity can actually be seen. Explanation is in the accompanying article https://trustica.cz/2018/04/05/elliptic-
From playlist Elliptic Curves - Number Theory and Applications
Tropical Geometry - Lecture 2 - Curve Counting | Bernd Sturmfels
Twelve lectures on Tropical Geometry by Bernd Sturmfels (Max Planck Institute for Mathematics in the Sciences | Leipzig, Germany) We recommend supplementing these lectures by reading the book "Introduction to Tropical Geometry" (Maclagan, Sturmfels - 2015 - American Mathematical Society)
From playlist Twelve Lectures on Tropical Geometry by Bernd Sturmfels
A positive proportion of plane cubics fail the Hasse principle - Manjul Bhargava [2011]
Arithmetic Statistics April 11, 2011 - April 15, 2011 April 11, 2011 (02:10 PM PDT - 03:00 PM PDT) Speaker(s): Manjul Bhargava (Princeton University) Location: MSRI: Simons Auditorium http://www.msri.org/workshops/567/schedules/12761
From playlist Number Theory
Tropical Geometry - Lecture 8 - Surfaces | Bernd Sturmfels
Twelve lectures on Tropical Geometry by Bernd Sturmfels (Max Planck Institute for Mathematics in the Sciences | Leipzig, Germany) We recommend supplementing these lectures by reading the book "Introduction to Tropical Geometry" (Maclagan, Sturmfels - 2015 - American Mathematical Society)
From playlist Twelve Lectures on Tropical Geometry by Bernd Sturmfels
algebraic geometry 17 Affine and projective varieties
This lecture is part of an online algebraic geometry course, based on chapter I of "Algebraic geometry" by Hartshorne. It covers the relation between affine and projective varieties, with some examples such as a cubic curve and the twisted cubic.
From playlist Algebraic geometry I: Varieties
Bitangents to plane quartics - tropical, real and arithmetic count by Hannah Markwig
PROGRAM COMBINATORIAL ALGEBRAIC GEOMETRY: TROPICAL AND REAL (HYBRID) ORGANIZERS Arvind Ayyer (IISc, India), Madhusudan Manjunath (IITB, India) and Pranav Pandit (ICTS-TIFR, India) DATE: 27 June 2022 to 08 July 2022 VENUE: Madhava Lecture Hall and Online Algebraic geometry is the study of
From playlist Combinatorial Algebraic Geometry: Tropical and Real (HYBRID)
Minerva Lectures 2013 - Terence Tao Talk 1: Sets with few ordinary lines
For more information please visit: http://math.princeton.edu/events/seminars/minerva-lectures/minerva-lecture-i-sets-few-ordinary-lines
From playlist Minerva Lecture Terence Tao
Complex surfaces 3: Rational surfaces
We give an informal survey of some complex rational surfaces. We first lift a few examples: hypersurfaces of degree at most 3, and the Hirzebruch surfaces which are P1 bundles over P1. Then we discuss the surfaces obtained by blowing up points in the plane in more detail. We sketch how to
From playlist Algebraic geometry: extra topics
This talk is about some properties of plane curves used in the Riemann-Roch theorem. We first show that every nonsingular curve is isomorphic to a resolution of a plane curve with no singularities worse than ordinary double points (nodes). We then calculate the genus of plane curves with o
From playlist Algebraic geometry: extra topics
Dominique Cerveau - Holomorphic foliations of codimension one, elementary theory (Part 4)
In this introductory course I will present the basic notions, both local and global, using classical examples. I will explain statements in connection with the resolution of singularities with for instance the singular Frobenius Theorem or the Liouvilian integration. I will also present so
From playlist École d’été 2012 - Feuilletages, Courbes pseudoholomorphes, Applications