EN
This paper treats the question of the existence of solutions of a fourth order boundary value problem having the following form:
$x^{(4)}(t) + f(t,x(t),x''(t)) = 0$, 0 < t < 1,
x(0) = x'(0) = 0, x''(1) = 0, $x^{(3)}(1) = 0$.
Boundary value problems of very similar type are also considered. It is assumed that f is a function from the space C([0,1]×ℝ²,ℝ). The main tool used in the proof is the Leray-Schauder nonlinear alternative.