TY - JOUR T1 - Remarks on solutions to the functional equations of the radical type AU - Brzdek, Janusz PY - 2017 DA - December DO - 10.31197/atnaa.379095 JF - Advances in the Theory of Nonlinear Analysis and its Application JO - ATNAA PB - Erdal KARAPINAR WT - DergiPark SN - 2587-2648 SP - 125 EP - 135 VL - 1 IS - 2 LA - en AB - This is an expository paper containing remarks on solutions to some functional equations of a form, that could be called of the radical type. Simple natural examples of them are the following two functional equations fn √xn + yn= f(x) + f(y),f n √xn + yn+ fn p|xn −yn|= 2f(x) + 2f(y) considered recently in several papers, for real functions and with given positive integer n, in connection with the notion of Ulam (or Hyers-Ulam) stability. We provide a general method allowing to determine solutions to them. KW - functional equation KW - radical type KW - Cauchy equation KW - quadratic equation CR - J. Aczél, J. Dhombres, Functional Equations in Several Variables, Cambridge University Press, Cambridge, 1989. CR - L. Aiemsomboon, W. Sintunavarat, On a new type of stability of a radical quadratic functional equation using Brzdek’s fixed point theorem, Acta Math. Hungar. 151 (2017), 35–46. CR - Z. Alizadeh, A.G. Ghazanfari, On the stability of a radical cubic functional equation in quasi- -spaces, J. Fixed Point Th. Appl. 18 (2016), 843–853. CR - N. Brillouët-Belluot, J. Brzdek, K. Cieplinski, On some recent developments in Ulam’s type stability, Abstr. Appl. Anal. 2012, Art. ID 716936, 41 pp. CR - Y.J. Cho, M. Eshaghi Gordji, S.S. Kim, Y. Yang, On the stability of radical functional equations in quasi- -normed spaces, Bull. Korean Math. Soc. 51 (2014), 1511–1525. CR - J. Dhombres, Some Aspects of Functional Equations, Chulalongkorn University Press, Bangkok, 1979. CR - I. EL-Fassi, Approximate solution of radical quartic functional equation related to additive mapping in 2-Banach spaces, J. Math. Anal. Appl. 455 (2017), 2001–2013. CR - I. EL-Fassi, On a new type of hyperstability for radical cubic functional equation in non-archimedean metric spaces, Results Math. 72 (2017), 991–1005. CR - H. Khodaei, M. Eshaghi Gordji, S.S. Kim, Y.J. Cho, Approximation of radical functional equations related to quadratic and quartic mappings, J. Math. Anal. Appl. 395 (2012), 284–297. CR - S.S. Kim, Y.J. Cho, M. Eshaghi Gordji, On the generalized Hyers-Ulam-Rassias stability problem of radical functional equations, J. Inequal. Appl. 186 (2012), pp. 13. CR - M. Kuczma, An Introduction to the Theory of Functional Equations and Inequalities, Panstwowe Wydawnictwo Naukowe & Uniwersytet Slaski, Warszawa–Kraków–Katowice, 1985. CR - E. Movahednia, H. Mehrannia, Fixed point method and Hyers-Ulam-Rassias stability of a radical functional equation in various spaces, Intl. Res. J. Appl. Basic. Sci. 5 (8) (2013), 1067–1072. CR - P. Narasimman, K. Ravi, S. Pinelas, Stability of Pythagorean mean functional equation, Global J. Math. 4 (2015), 398–411. CR - J. Olko, M. Piszczek (eds.), Report of meeting: 16th International Conference on Functional Equations and Inequalities, Bedlewo, Poland, May 17–23, 2015, Ann. Univ. Paedagog. Crac. Stud. Math. 14 (2015), 163–202. CR - S. Phiangsungnoen, On stability of radical quadratic functional equation in random normed spaces, IEEE Xplore Digital Library, 2015 International Conference on Science and Technology (TICST), 450–455. DOI: 10.1109/TICST.2015.7369399 UR - https://doi.org/10.31197/atnaa.379095 L1 - https://dergipark.org.tr/en/download/article-file/596296 ER -