| This article is divided into three parts.The main research is about the sum-sets of weighted exceptional units in a finite commutative ring and the number of solutions of diagonal quadratic forms over Galois rings GR(p2,p2m).The paper is organized as follows:In Chapter 1,we introduce the definition of finite communicative rings with identity and Galois rings,the backgrounds of the representation of weighted excep-tional units and quadratic diagonal forms.Let R be a finite commutative ring with identity.In Chapter 2,we obtain a formula for the number of ways to represent each element of R to the sum of some weighted exceptional units.Let R=GR(p2,p2m)be a Galois ring and N(a1x12+…+anxn2=b)denote the number of solutions of quadratic diagonal forms a1x12+…+anxn2=b,where a1,…,an∈R*,x1,…,xn,b∈R.Our main result in chapter 3 is to get formulae of N(ax2 =b),N(a1x12+ a2x22= b)and N(a1x12+ a2x22+a3x32= b). |