Assigning a variable to symbolically solved matrix

Hello everyone, I'm having some big problems trying to solve a finite element method problem for my class. I am trying to determine a stiffness matrix for a problem I was assigned and this requires me to double integrate an 8x3 matrix, a 3x3 matrix, and a 3x8 matrix. I get mathcad to perform the matrix multiplication to give me an 8x8 matrix, even though it says the symbolic value is too large to display. However the issue is, I cannot assign a variable to the result that I am got, I do not understand how to get this to work, when I know mathCAD should be able to do the computation. Below attached is the exact solution to what I am talking about. Please help!