In this paper, first the authors obtain the nonexistence of nontrivial solutions for the linear Dirichlet boundary value problem with impulses
{x″(t)+a(t)x(t)=0,t≠τk,Δx(τk)=ckx(τk),Δx′(τk)=dkx(τk),x(0)=x(T)=0,(k=1,2⋯,m)
where
a:[0,T]→R,
ck and
dk are
constants,
k=1,2,⋯,m,
Δx(τk)=x(τ+k)−x(τ−k),
Δx′(τk)=x′(τ+k)−x′(τ−k),
0<τ1<τ2<⋯<τm<T.
Secondly, by applying Leray-Schauder degree, the authors obtain the existence and uniqueness of solutions for the nonlinear Dirichlet boundary value problem with impulses
{x″(t)+f(t,x(t))=0,t≠τk,Δx(τk)=Ik(x(τk)),Δx′(τk)=Mk(x(τk)),x(0)=x(T)=0,(k=1,2⋯,m)
where
f∈C([0,T]×R,R),
Ik,Mk∈C(R,R),
k=1,2,⋯,m.
As a corollary of the results, the Lyapunov inequality is extended to impulsive systems.