Electronic Journal of Differential Equations, Vol. 2013 (2013), No. 36, pp. 1-14. Title: Positive solutions for a 2nth-order p-Laplacian boundary value problem involving all derivatives Authors: Youzheng Ding (Shandong Univ., Jinan, China) Jiafa Xu (Shandong Univ., Jinan, China) Xiaoyan Zhang (Shandong Univ., Jinan, China) Abstract: In this work, we are mainly concerned with the positive solutions for the 2nth-order p-Laplacian boundary-value problem $$\displaylines{ -(((-1)^{n-1}x^{(2n-1)})^{p-1})' =f(t,x,x',\ldots,(-1)^{n-1}x^{(2n-2)},(-1)^{n-1}x^{(2n-1)}),\cr x^{(2i)}(0)=x^{(2i+1)}(1)=0,\quad (i=0,1,\ldots,n-1), }$$ where $n\ge 1$ and $f\in C([0,1]\times \mathbb{R}_+^{2n}, \mathbb{R}_+)(\mathbb{R}_+:=[0,\infty))$. To overcome the difficulty resulting from all derivatives, we first convert the above problem into a boundary value problem for an associated second order integro-ordinary differential equation with p-Laplacian operator. Then, by virtue of the classic fixed point index theory, combined with a priori estimates of positive solutions, we establish some results on the existence and multiplicity of positive solutions for the above problem. Furthermore, our nonlinear term f is allowed to grow superlinearly and sublinearly. Submitted September 10, 2012. Published January 30, 2013. Math Subject Classifications: 34B18, 45J05, 47H1. Key Words: Integro-ordinary differential equation; a priori estimate; index; fixed point; positive solution.