Set Multiplication

**jonnysteals** · December 6th 2006, 05:05 AM

Im going over old material of mine and cant remember how to multiply simple sets together. The sets I am trying to multiply together are {1,2,3} x {4,5}. Any anwsers would be very useful. Thanks Jon

**TriKri** · December 6th 2006, 05:57 AM

Originally Posted by jonnysteals

Im going over old material of mine and cant remember how to multiply simple sets together. The sets I am trying to multiply together are {1,2,3} x {4,5}. Any anwsers would be very useful. Thanks Jon

I have never heard of set multiplication before. Maybe someone else at this forum has. Are you sure you didn't intend to do a form of matrix multiplication,

$\left(\begin{array}{c}1\\2\\3\end{array}\right)\ti mes\left(\begin{array}{cc}4&5\end{array}\right)\ =\ \left(\begin{array}{cc}<br /> 4&5\\<br /> 8&10\\<br /> 12&15<br /> \end{array}\right)$

**Plato** · December 6th 2006, 06:25 AM

Originally Posted by jonnysteals

trying to multiply together are {1,2,3} x {4,5}.

Usually that notation is for ‘cross products (Cartesian Products)’.
$\left\{ {1,2,3} \right\} \times \left\{ {4,5} \right\} = \left\{ {\left( {1,4} \right),\left( {2,4} \right),\left( {3,4} \right),\left( {1,5} \right),\left( {2,5} \right),\left( {3,5} \right)} \right\}.$

**TriKri** · December 6th 2006, 06:42 AM

Aha, all different combinations one from each set. I have to read more courses.

**jonnysteals** · December 6th 2006, 07:10 AM

Yea if I had to guess thats what I would have guessed but I figured Id ask the more knowledge people on these boards. Thanks Jon. You guys respond very quick; I'm Impressed!.

**Soroban** · December 6th 2006, 07:16 AM

Hello, Jon!

The sets I am trying to multiply together are {1,2,3} x {4,5}.

As I recall, set multiplication doesn't involve arithmetic, just pairing.

$\{1,2,3\} \times \{4,5\} \;=\;\{(1,4),\,(1,5),\,(2,4),\,(2,5),\,(3,4),\,(3, 5)\}$

You see, set multiplication can be performed with sets like:
. . $\{\text{shoes},\text{ ships},\text{ sealing wax}\}$ and $\{\text{cabbages},\text{ kings}\}$

Thread: Set Multiplication

LinkBack

Thread Tools

Display

Set Multiplication

Similar Math Help Forum Discussions

[SOLVED] Multiplication

Multiplication

Multiplication mod 2

multiplication

Multiplication Law?

Search Tags