hubFS: THE place for F#

I am really enjoying Expert F#. In the section titled "Example: Using F# Quotations For Error Estimation" (on p. 251 of Chapter 9), I am wondering whether the derivation for the errors is correct for multiplication and division.

According to my derivations, I have:

        instead of //(x*y,Err(xerr*abs(x)+yerr*abs(y)+xerr*yerr))
        (x*y,Err(abs(x)*yerr+abs(y)*xerr+xerr*yerr))
        for multiplication

        instead of //(x/y,Err(xerr*abs(x)+abs(1.0/y)/yerr+xerr/yerr))
        let xa,ya = abs(x), abs(y)
        (x/y,Err((xa*yerr+ya*xerr)/(ya*(ya-yerr))))
        for division

Does anyone else agree that the book's derivations are wrong, or am I missing something?

Thanks. ~n