should I use real numbers ??
I have a maths question which reads:
Let M be the set of all real 2 * 2-matrices of the form:
Show that this set of matrices is closed under matrix multiplication, and that matrix multiplication is commutative on this set.
Should I use real numbers to solve this problem or use what the question gave??
Re :should I use real numbers ??
I forgot to mention.. the attached image is the matrix given in the question.
Re: should I use real numbers ??
Originally Posted by CaptainBlack
Thankyou for your help.
I believe I've got it now..
Here's how I'm going to completely answer the question:
Let a,b,c,d,e,f be real numbers:
[a 0] [c 0] = [e 0]
[0 b] [0 d] = [0 f]
.: M is closed under matrix multiplication because the product of two M members is also in the M set.
Let A = [a 0]
B = [b 0]
AB = [ab 0]
BA = [ab 0]
AB = BA
.: matrix multiplication is commutative on this set.