This is the question I got on my final assignment (Calculus III):
Evaluate the surface integral
\begin{equation} \int \int_S xy \; \; dy\wedge dz - yz \; \; dz\wedge dx + xz \; \; dx\wedge dy \end{equation}
Where $S$ is the part of the plane $x+y+z=1$ lying in the first octant. Use $x$ and $y$ as parameters.
I am quite confused. I asked around and someone told me that this is also the symbol for something called the Wedge product, which I've not heard of before and appears in neither my calculus textbooks (Stweart's and Div Grad Curl) nor any of my Linear Algebra books.
From what I saw online, I still don't understand how it would make sense in this equation.
Is this a typo? Seems like a strange typo. Should it just read:
\begin{equation} \int \int_S xy \; \; dydz - yz \; \; dzdx + xz \; \; dxdy \end{equation}