On Dirichlet problems with singular nonlinearity of indefinite sign

Abstract

Let Ω be a smooth bounded domain in RN , N ≥ 1, let K, M be two nonnegative functions and let α, γ > 0. We study existence and nonexistence of positive solutions for singular problems of the form −Δu = K(x)u−α − λM (x)u−γ in Ω, u = 0 on ∂Ω, where λ > 0 is a real parameter. We mention that as a particular case our results apply to problems of the form −Δu = m(x)u−γ in Ω, u = 0 on ∂Ω, where m is allowed to change sign in Ω.