Matrix multiplication, specifically elimination matrices.

[AJBMuir]

I was wondering if anybody can see where I have gone wrong here?
I was given the rule, E2(E1A1)=(E2E1)A1, I can't seem to find my mistake.

 

[tiny-tim]

Hi AJBMuir!

I was wondering if anybody can see where I have gone wrong here?
I was given the rule, E2(E1A1)=(E2E1)A1, I can't seem to find my mistake.View attachment 60702

Your (E₂E₁)A is wrong …

eg the top-right should be 4 -2 + 2

 

[AJBMuir]

Hi AJBMuir! Your (E₂E₁)A is wrong …

eg the top-right should be 4 -2 + 2

Cheers, I have no idea how I missed that!