{ 3 2 } x { a b } = { 1 0 }

{ 1 -1 } { c d } { 0 1 }

So, what is:

{ a b } = { 1 0 } x Inv. { 3 2 }

{ c d } { 0 1 } { 1 -1 }

can any help me figure it out this matrix

its do to with "inverse"

thanks in advance

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- Feb 15th 2009, 05:55 AMkarimwahabmatrix multiplication
{ 3 2 } x { a b } = { 1 0 }

{ 1 -1 } { c d } { 0 1 }

So, what is:

{ a b } = { 1 0 } x Inv. { 3 2 }

{ c d } { 0 1 } { 1 -1 }

can any help me figure it out this matrix

its do to with "inverse"

thanks in advance - Feb 15th 2009, 08:07 PMCaptainBlack
- Feb 16th 2009, 08:21 AMGrandadInverse of a 2x2 matrix
Hello karimwahabI'm not entirely sure what you mean by the part in red, but the first part is clear enough. It is:

Now the matrix is called the*Identity Matrix*, usually denoted by . This matrix has the special property that when any other 2x2 matrix is multiplied by it (either on the left or the right) then that matrix is unchanged - it keeps its*identity*. In other words, for any matrix :

You then need to know that, if and are 2x2 matrices and , then and are*inverses*of each other. This is written and .

So the matrix is the inverse of the matrix . There's a formula for the inverse of a 2x2 matrix here: The inverse of a 2x2 matrix - mathcentre

If you use that formula, you'll find that:

I hope that answers the question.

Grandad

- Feb 16th 2009, 11:02 AMstapel
If you're not familiar with the general process, try some online lessons regarding

**finding matrix inverses**.

If you are asking how to complete the exercise, try some online lessons regarding**matrix multiplication**. (**This lesson**has an animation that some students find helpful.)

Have fun! :D