Thread: Matrix multiplication.

to prove
Η * Η’ = Η’ * Η

Η= [a b]
[c d]


H'=[a' b']
[c' d']

Do the multiplication matrix and show us what you get!

i Do the multiplication and i find a='a and d='d
but my teacher say a’ = a b’ = c c’ = b and d’ = d

And




Well, I'm not sure what you are trying to do, but your original post says prove that H.H' = H'.H

Since we know that a = a', d = d', c = b' and b = c', then H.H' = H'.H is proved.

we dont know that a = a', d = d', c = b' and b = c',
we are trying to find that h*h'=h'*h
and i think that the anser is a = a', d = d', c = b' and b = c',
but i am not completely sure

Well, for H.H' to be equal to H'.H, we must have a = a', d = d', c = b' and b = c'

thnks dude!
may the force be with you!!

Uh...okay...

Thanks!

sorry can you explain the answer plzzzzz??

You cannot prove that

H.H' = H'H

unless we know that a = a', d = d', c = b' and b = c'

All you appear to have here is two unrelated matrices, H and H'.

You cannot then prove that "H*H'= H'*H" because it is not true: matrix multiplication is not commutative.

Or did you mean that H' is the transpose of H? No, that doesn't work either. So I don't know what you are asking.