Nevermind. I discovered that the proportion between the integrals was y=0,25*x^-1 - Two very complex integrals turned into a very easy thing.
EDIT: What kind of file should I be using? and Do you know a program which is always able to show the integral as a function? - unlike Ti-interactiv.
double left mouse on the formula to see how to write it ...
here's link where u have many commands ...
LaTeX:Commands - AoPSWiki
I suppose that a PDF would be much less dangerous to open. If you are running Windows you can convert your Word document to PDF with PDFCreator (http://sourceforge.net/projects/pdfcreator/)