#1

If I have a problem like this

Find 3XY. Where X and Y are two different matrices, am I supposed to do the scaler multiplication first (multiplying 3 to matrix X) or am I supposed to multiply X and Y and THEN multiply 3 to the product matrix of X and Y?

Find 3XY. Where X and Y are two different matrices, am I supposed to do the scaler multiplication first (multiplying 3 to matrix X) or am I supposed to multiply X and Y and THEN multiply 3 to the product matrix of X and Y?

#2

That shouldn't matter, should it? Shouldn't you get the same answer?

#3

i dunno, i was captivated by ur avatar.

#4

Believe in SteveHouse.

#5

it'll be easier if you multiply the matrices first, then multiply your answers by 3

#6

hmm i used to know how to do this 2 years ago.... damn

#7

Believe in SteveHouse.

*waits for other guy*

#8

Dude... I feel like I haven't seen you in forever.

#9

i think you multiply both Matrices, then multiply by 3.

#10

Multiplication is commutative. You can multiply them in any order and you'll get the same answer. As long as you know how to multiply the matrices, you're set. Just ignore the 3 until the end, that's what I do.

#11

Actually, matrix multiplication isn't commutative... X Y =/= Y X

but it IS associative, 3 (X Y) = (3 X) Y, so TS, you can do any of the things you mentioned and get the same result.

but it IS associative, 3 (X Y) = (3 X) Y, so TS, you can do any of the things you mentioned and get the same result.

#12

I sleep on mattresses.

What the **** do they have do to with maths?

What the **** do they have do to with maths?

#13

Multiplication is commutative. You can multiply them in any order and you'll get the same answer. As long as you know how to multiply the matrices, you're set. Just ignore the 3 until the end, that's what I do.

Matrix multiplication ain't commutative- XY =/= YX inherently. Can be in special cases (

But yeah, you can multiply X or Y by 3 before dealing with the matrices, or leave the 3 out and multiply the result by 3. I'd go for the latter myself, smaller numbers mean less chance to mess up, but both would get you to the same answer providing you did it right.

#14

Back of the book.

#15

Actually, matrix multiplication isn't commutative... X Y =/= Y X

but it IS associative, 3 (X Y) = (3 X) Y, so TS, you can do any of the things you mentioned and get the same result.

That sounds right.

Do the matrices first, then multiply by 3, it will be easier.