Let and let D(I) and denote the space of infinitely differentiable complex-valued functions with compact support on I and , respectively. The dual of these spaces will be denoted by prime. Let the operators , and Q from into D(I) be given by and Their adjoint are , and . If satisfy equation
then there exist a,b,c such that and for . For regular distributions equation (P) reduces to the Pexider equation . Generalizations of another Pexider equation are also considered.