Determinants are usually introduced in Linear algebra out of the blue because you can't get to other important topics in Linear Algebra without them. Calculatin

Determinants are usually introduced in Linear algebra out of the blue because you can't get to other important topics in Linear Algebra without them. Calculating them is a complex mess best left for a calculator. Sheldon teaches Linear Algebra as a theoretical math course, along the lines of learning Abstract Algebra. He approaches those other important topics from a different direction entirely, and determinants are just a trivial part of his book because of the different approach.