Okay, I'm total shite with math,if anyone remembers how to do this stuff, I need to find the inverses of matrices, if there is one in the problem.

Can anyone do one as an example and just show me what to do?

5 0
0 1

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quote:

Originally posted by Pariah Cleric Okay, I'm total shite with math,if anyone remembers how to do this stuff, I need to find the inverses of matrices, if there is one in the problem. Can anyone do one as an example and just show me what to do? 5 0 0 1

-1 0
0 -5


its been 4 years since ive did them but im pretty sure thats how its done

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...I'll be back for breakfast

EDIT:

[5 0] [x11 x12] = [1 0]
[0 1] [x21 x22] [0 1]

[5x11 + 0x21 5x12 + 0x22 ] = [1 0]
[0x11 + 1x21 0x12 + 1x22 ] [0 1]

5x11 + 0x21 = 1 5x12 + 0x22 = 0
0x11 + 1x21 = 0 0x12 + 1x22 = 1

5x11 = 1 5x12 = 0
1x21 = 0 1x22 = 1

x11 = 1/5, x21 = 0, x12 = 0, x22 = 1

[1/5 0]
[0 1]

check:
[5 0] [1/5 0] = I
[0 1] [0 1]

[5(1/5)+0 0+0] = I
[0+0 0+1]

[1 0] = I
[0 1]

Last edited by ierxium on Jan-17-2006 at 00:20

Math is gay! I will never do another math problem!

Thank you H&R Block!

at the bottom in quotes is how to do it, in simple terms.

what kind of inverse are u trying to find? there is additive, and multiplicative inverses, and both are different. the obvious is additive, where u take the original matrix, add it by its inverse to get all zeros in the answer. with a multiplicative inverse, u make the original matrix multiplied by its inverse = to
[1 0]
[0 1]

make it into an algebraic equation. matrix A (x or +) matrix (inverse which is unknown) = (0 1 0 1 matrix for multiplicative) or (matrix with all zeros for additive)

hope u know what identity and all that shit is.
----------------------
take a graphing calculator, preferably a texas instrument TI-83+.

enter the values into a matrix in the calculator. if u dont know how to do that, find out.

then get matrix A, which is the values for your matrix, and just put a -1 as its exponent, and youll get your answer.
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quote:

Example 1: Find the multiplicative inverse of Find click this link for an example of multiplicative inverse shown simply

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Last edited by Krypton on Jan-17-2006 at 01:28

matrices are essential in life.
without matrices, you will not have your rpg video games.
without matrices, there would be no world of warcraft and unreal tournament.

by the way :
[5 0] | [1 0]
[0 1] | [0 1]

==

[((5*1)+(0*0)) ((5*0)+(0*1)) ]
[((0*1)+(1*0)) ((0*0)+(1*1)) ]

==

[5 1]
[0 1]

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[5 0] [x11 x12] = [1 0]
[0 1] [x21 x22] [0 1]

[5x11 + 0x21 5x12 + 0x22 ] = [1 0]
[0x11 + 1x21 0x12 + 1x22 ] [0 1]

5x11 + 0x21 = 1 5x12 + 0x22 = 0
0x11 + 1x21 = 0 0x12 + 1x22 = 1
--------------- ---------------
5x11 + 1x21 = 1 5x12 + 1x22 = 1

quote:

Originally posted by ierxium [5 0] [x11 x12] = [1 0] [0 1] [x21 x22] [0 1] [5x11 + 0x21 5x12 + 0x22 ] = [1 0] [0x11 + 1x21 0x12 + 1x22 ] [0 1] 5x11 + 0x21 = 1 5x12 + 0x22 = 0 0x11 + 1x21 = 0 0x12 + 1x22 = 1

5x11 = 1 5x12 = 0
1x21 = 0 1x22 = 1

x11 = 1/5, x21 = 0, x12 = 0, x22 = 1

[1/5 0]
[0 1]

check:
[5 0] [1/5 0] = I
[0 1] [0 1]

[5(1/5)+0 0+0] = I
[0+0 0+1]

[1 0] = I
[0 1]

fellas, we are genious

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quote:

Originally posted by ::TranceVanDyk:: fellas, we are genius

Fixed.

Thanks a ton, guys. It's actually really simple, the book we have just makes it crazy hard to understand.

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