where 839e52661c0a390bac5e7fb5eb2a3" title="Click to view the MathML source">λ0 is an arbitrary real number and 8cd6bc9adc95747cac9ac753" title="Click to view the MathML source">λ1,λ2∈R with e7ecb67ec99951ec8c2c32" title="Click to view the MathML source">λ2≠0 and e50cd12f91dca34d8627869aac1"> not in 909c345694b25f075c576" title="Click to view the MathML source">Q. This improves a result by Harman.