Math Matrixes

I am struggling with this idea and it is bothering me

Matrixes are classified by their

Matrices are usually written in square brackets and they are commonly classified by their dimension

lower triangular matrix

Matrix D might be called a lower triangular matrix, because all the entries above the main diagonal are 0:

zero matrix

Sometimes, matrices like [H] have entries that are all 0s. [H] is known as the 2×2 zero matrix or null matrix, which is notated

Identity Matrices

Diagonal matrices whose entries on the main diagonal are all 1s are called identity matrices.

When can we multiply matrices by each other

Multiplying Matrices By each other

Multiplying matrices does not commute (that means A * B does not mean B x A). We also go along each item in a row from the first matrix and multiply by the column of the second matrix. We multiply each but then, ADD each product together to fill in

Identity and 0 matrixes

Matrix Determinant 2×2

Matrix Determinant 3×3

Matrix Inverse 2×2

Long story short, you cannot divide with matrices. So you have to multiply both sides by the reciprocal on the left, that will leave an identity matrix which is like 1.