Originally Posted by

**Awesome31312** So, it's my very first exposure to higher math. I got As all the way from Calc I-III including Dif eq, but now, I find myself unable to solve ANY linear algebra problem from Gilbert Strang's course on MIT OCW..

Well, actually I can do problem 6.2 (3.2 # 18 in his book), but I need help with this subspace problem:

Problem 6.1: (3.1 #30. Introduction to Linear Algebra: Strang) Suppose **S**and **T **are two subspaces of a vector space **V**.

a) The sum **S + T **contains all sums **s + t** of a vector **s **in **S **anda vector **t **in **T**. Show that **S + T** satisfies the requirements (addition andscalar multiplication) for a vector space.

b) If **S **and **T **are lines in **R^**m, what is the difference between **S + T **and**S **∪** T**? That union contains all vectors from **S **and **T **or both. Explainthis statement: *The span of* S ∪ T is S + T.

Also, does anybody have any advice on how to study for this course? The chapters in the book, the lectures, recitation contain absolutely **Nothing **about the union and all that..