math integration characters

[Tuukka Toivonen]

I have been teached to mark integrals like this:

        b        b
       /\       /      2         2         2
      / xdx =  / (1/2)x  = (1/2)b  - (1/2)a
    \/        /
    a        a

Now the problem: how to get the "/" character? It's a little bit
like a large slash, but simply a slash isn't quite an acceptable
character. I'd like also to get the limits directly above and
below the "/" character.