“…In [9], let η = λ, f (x,u) = λ u r , λ > 0 and 0 < r < 1, the author got that system (1.1) has at least two positive solutions and one of the solutions is a ground state solution for all λ ∈ (0,λ * ), where λ * is a positive constant. In [10], assuming that η = −1, f (x,u) = λ u r , λ>0 and 0<r <1, the authors proved that system (1.1) has at least two positive solutions for all λ ∈ (0,λ * ), where λ * is a positive constant. In [11], let η = 1, f (x,u) = λ |x| β u r , λ > 0, 0 < r < 1 and 0 ≤ β < 5+r 2 , combining with the variational method and Nehari manifold method, two positive solutions of system (1.1) are obtained.…”