Muñoz-Fernández, Gustavo A.Seoane Sepúlveda, Juan Benigno2023-06-202023-06-202008-04-150022-247X10.1016/j.jmaa.2007.09.010https://hdl.handle.net/20.500.14352/50195For each pair of numbers m, n epsilon N with m > n, we consider the norm on R-3 given by parallel to(a, b, c)parallel to m,n = sup{vertical bar ax(m) +bx(n) +C vertical bar: x epsilon [-1, 1]} for every (a, b, c) epsilon R-3. We investigate some geometrical properties of these norms. We provide an explicit formula for parallel to center dot parallel to m,n, a full description of the extreme points of the corresponding unit balls and a parametrization and a plot of their unit spheres.engjournal articlehttp://www.sciencedirect.com/science/article/pii/S0022247X07011237http://www.sciencedirect.com/restricted access517.98ConvexityExtreme pointsPolynomial normsTrinomialsAnálisis funcional y teoría de operadores