These are basically rules of matrix multiplication.

The product of two matrices is quite difficult as a starter because it does not follow conventional rules of multiplication all the time, unlike the addition or subtraction of matrices which are rather straightforward.

i have learnt multiplication of matrices. i understand the last property but i dont really understand the rest... especially the 3rd one as i thought they are equal
for the first 2 ones, i dont know what they are talking about

Unlike regular multiplication, matrix products are non-commutative. This means that matrix A multiplied by matrix B will in general be different from matrix B multiplied by matrix A.

ohh... what does the 1st 2 property mean tho

In general, the matrix multiplication is not commutative.

However, there are exceptions. Point 1 involves the multiplication of a zero matrix, and the result of the multiplication will be a zero matrix in either order. Point 2 involves the multiplication of an identity matrix, where any matrix M multiplied to this identity matrix (or vice versa) will get back the same matrix M either way.

thx :) btw are you able to help with some questions today? i have posted the questions just now

Not yet free for these few days

I have a little time to spare for now, but I won’t be free for at least two days afterwards

there is a logarithms question with i have posted this morning and it was answrred by another tutor. however, her answer for part b and c is wrong tho...
for part b, i have actually gotten the same answer as her

Tutor is ok for part b, went careless on c