I posted a question, which I have attempted all except for c. Could someone tell me if I did the question correctly? And how do I begin (c). Thanks, there is a PDF file attached.
finally in order to show that a non-empty set is a subspace you do not need to prove that it contains unfortunately some instructors give this wrong idea to some students.
for part (b), the basis you found is wrong! you should at least see that none of the elements of the set that you think is a basis basically belongs to anyway, a basis of
has only one element. for example
for part (c) first see that an matrix with real (or complex) entries, is antisymmetric iff for all and for all can you
see the general form of ? if not, try to do it for n = 3 first. now it should be easy to show that a basis for antisymmetric matrices has elements. what are they?
The reason why we often do prove that the 0 vector is in the set is simply to prove it is non-empty- and 0 is typically easiest to work with. Here, you are asked to show that the set of anti-symmetric 2 by 2 matrices is a subspace and I would disagree with millerst- you are NOT given that it is non-empty, you need to show that. Of course, you could do that as well by showing that is in the set as by showing that is in the set.