Saturday

January 21, 2017
Posted by **harry** on Saturday, December 6, 2008 at 6:18pm.

2 1

-3 4

Find

2x+y=2

-3x+4y=1

- math -
**harry**, Saturday, December 6, 2008 at 6:20pmIt is supposed to be a matrix.

2, 1

-3, 4

but i donot know how to put the brackets. i used commas to separate the numbers - math -
**Damon**, Saturday, December 6, 2008 at 7:26pmwell, I will use gauss jordan, see the link I gave you.

2,1,1,0

-3,4,0,1

+1, .5 , .5, 0

-3, 4. , 0 , 1

multiply top by +3 and add to bottom

+1, .5 , .5 , 0

0 , 5.5, 1.5, 1

divide second row by 5.5

+1, .5 , .5 , 0

0 ,1.0, .273,.182

subtract half the second row from the first to get a new first

+1 , 0 , .364, -.091

0 , 1.0, .273, .182

so I think the inverse is

.364 , -.091

.273 , .182

multiply that by

2

1

and get

x = 2*.364 - 1* .091 = .637

y = 2*.273 +1 * .182 = .728

check

2*.637 + .728 = close enough to 2

-3*.637 + 4*.728 = close enough to 1- Took me a while -
**Damon**, Saturday, December 6, 2008 at 7:28pmI have not inverted a matrix by hand for a while :)

- Took me a while -