Problems(1)
Let m,n≥2 be positive integers, and let a1,a2,⋯,an be integers, none of which is a multiple of mn−1. Show that there exist integers e1,e2,⋯,en, not all zero, with ∣ei∣<m for all i, such that e1a1+e2a2+⋯+enan is a multiple of mn. modular arithmetic