Formatting big matrix and ratios using multi-row entries [closed]

It is possible to write the denominator or the numerator of a ratio, as well as the entries of a matrix, in multiple rows? This could be helpful in order to format long equations inside a document.

Thanks. please excuse me if my question was incomplete. I would like to create matrices or ratios with big entries in two or more that one row. As Werner suggested a solution could be:

$$\begin{array}{cc} \begin{array}{c} 3 +\\ 4 x \end{array} & \begin{array}{c} 3 +\\ 4 x \end{array} \\ \begin{array}{c} 3 +\\ 4 x \end{array} & \begin{array}{c} 3 +\\ 4 x \end{array} \end{array}$$


Now the problem is that it would be important to add more space between the entries in order to distinguish between rows belonging to different entries.

-
well I would start clicking the tags and seeing what can be achieved. Otherwise, unfortunately, this is a discussion but not a Q&A. Or you can include a special case to allow others generalize that, –  percusse Feb 14 '13 at 1:19
Welcome to TeX.SE. It is not clear to me what you desire. It would be helpful if you composed a fully compilable MWE including \documentclass and the appropriate packages that would clarify and set up the problem. While solving problems can be fun, setting them up is not. Then, those trying to help can simply cut and paste your MWE and get started on solving the problem. There will also be less confusion if you show what the desired output should be. –  Peter Grill Feb 14 '13 at 1:48
Yes, this is possible. You can nest an array inside a fraction or an equation to stack content. –  Werner Feb 14 '13 at 1:52
maybe \splitfrac from mathtools package will be of help. see pp 31 in The mathtools package –  Zarko Feb 14 '13 at 11:08