Hi, I need some help solving this homogeneous differential equation with constant coefficients for initial condition;

y''''-4y=0

and

y(0)=1

y(1)=0

y(-1)=0

y(inf)=0

Well I get as far as

y=C1*e^(x*sqrt(2)) + C2*e^(-x*sqrt(2)) + C3*cos(x*sqrt(2)) + C4*sin(x*sqrt(2)),

but I don't know how to solve for initial contritions and would appreciate any help.

Well I think that

c1+c2+c3=1,

but that is as far as I get.