00:01
Okay, so let's get started with i.
00:03
Well, here we have v, which is the set consisting of matrices a, b, c, d belonging to m2 times 2, so the vector space of 2 times 2 matrices, such that a plus b minus 3c plus d is equal to 0.
00:26
Okay, well, this guy here is a subspace.
00:32
Of m2 times 2 because it is defined by using a homogeneous linear equation in the entries of our matrices.
00:46
So that's why this guy is a subspace.
00:50
Now let's take a look at double i.
00:53
Well, this guy here is not a subspace, not a subspace because the zero matrix.
01:09
Does not belong to our set of all two times two matrices, such that a x equals zero has a non -trivial solution...