00:01
Okay, so let's get started with a.
00:03
Well, a is a subspace of two times two matrices.
00:09
So in particular, it is going to be a vector space.
00:13
Now, let's take a look at b.
00:17
Well, the set of all two times two triangular matrices, well, again, this one is a subspace.
00:26
Now, let's take a look at c.
00:29
The set of all two two triangular matrices, well, again, this one is a subspace.
00:30
Times two lower triangular matrices well this one is going to be a subspace again because any linear combination of lower triangular matrices is going to be a linear a lower triangular matrix now let's take a look at d okay i want to use black here okay the set of all two times two matrix is a with a one two equals one well this one is not a subspace they should is that the matrix 0 -0 does not belong to this subset...