Journal of the Chungcheong Mathematical Society (충청수학회지)
- Volume 20 Issue 4
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- Pages.387-399
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- 2007
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- 1226-3524(pISSN)
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- 2383-6245(eISSN)
GENERALIZED HYERS-ULAM STABILITY OF FUNCTIONAL EQUATIONS
- Kwon, Young Hak (Seoul Science High School) ;
- Lee, Ho Min (Seoul Science High School) ;
- Sim, Jeong Soo (Seoul Science High School) ;
- Yang, Jeha (Seoul Science High School) ;
- Park, Choonkil (Department of Mathematics Hanyang University)
- Received : 2007.09.17
- Published : 2007.12.31
Abstract
In this paper, we prove the generalized Hyers-Ulam stability of the following linear functional equations f(x + iy) + f(x - iy) + f(y + ix) + f(y - ix) = 2f(x) + 2f(y) and f((1 + i)x) = (1 + i)f(x), and of the following quadratic functional equations f(x + iy) + f(x - iy) + f(y + ix) + f(y - ix) = 0 and f((1 + i)x) = 2if(x) in complex Banach spaces.
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