Question

Find the inverse matrix of:
{-4x+y=5
{x-3y=4

Answer 1

How would you set up the matrix itself?

Answer 2

[-4 1 | 5]
[1 -3 | 4]

Answer 3

not quite sure you can find the inverse of a matrix like that...

i think it would be something like this

[-4 1][x] [5]
[1 -3][y] = [4]

Answer 4

How do you find x and y?

Answer 5

it isn't really asking for x and y, it only wanted the inverse matrix... but now I'm not quite sure how you could figure it out with my way either. :x

Sorry, might have to find somebody else, this isn't my strongpoint. :(

Answer 6

okay, this is how u'd set up the matrix (im 90% sure):
[-4 1]
[1 -3]
and now just get it's inverse.. for that, just multiply it by the identity matrix, so your inverse would be:
[-4 1] [1 0]
[1 -3] [0 1]

Answer 7

multiplying by the identity gets you the same matrix tho... I think the inverse is defined by

[a b] -1 [d -b]
[c d] = [-c a] * determinant of the matrix

Answer 8

wait.. im sure u had to multiply it by some other matrix..

Answer 9

but u're right, i was being an idiot

Answer 10

when you multiply the inverse by the right side of that equation i posted, that gets you the answer... but I didn't think that was the inverse, and that's what caught me up here. :P

Answer 11

lol good answer mate

Answer 12

[-4 1] -1
[ 1 -3]

[-3 -1]
[-1 -4] * det(original matrix)

det(original matrix) = -4*-3 - 1 = 12 - 1 = 11

[-3 -1]
[-1 -4] * 11
[-33 -11]
= [-11 -44]

is what i get for that inverse