I want to solve boundary value problem in n points, x_{n}\in(0,1):

-u'(x)(ku'(x))=12x^{2}

where:
u(x)\in[0,1]
u(0)=0
ku'(1)+hu'(1)=hu_{z}
x\in R
with finite difference method instead of finite element method.

I substituted finite difference:
u'(x)=\frac{u(x_{i-1})-u(x_{i+1})}{2h}
h=\frac{1}{n}

and obtained:
-kn^{2}[u(x_{i-1})-u(x_{i+1})]^{2}=3x_{i}^{2}
i=1,...,n

And I don't know how to turn that into the matrix equation. Is there a way to do it?