Multiplicity of positive solutions for a singular and critical problem

In this paper, we study the following singular, critical elliptic problem : (Pλ){−Δu=λ(u−δ+uq+ρ(u))inΩu|∂Ω=0,u>0inΩ where Ω⊂RN(N≥3)Ω⊂RN(N≥3) is a bounded domain with smooth boundary ∂Ω,λ>0,δ>0∂Ω,λ>0,δ>0, 1