You will not need to know matrix multiplication on the way in the door for the material covered in Stewart's text. You'll develop the necessary basics of linear algebra - euclidean distance, inner product, cross product, etc - during the course. Do go back and review differentiation and antidifferentiation. For now, you can set aside the material on sequences and series, although I *highly* recommend that you review that because it will come back farther along in your studies. I highly encourage you to review implicit differentiation, the chain and product rules of differentiation, 'u-substitions,' integration by parts, trig substitutions and polar coordinates now.