test tommorow, quick math question

[Semidevil]

ok, it is me, and I have a linear algebra question.

here is an example question:

given the set (3, 4) ( -1, 1) (2,0)
I need to find a linear combonation whose sum is zero vector,

so basically, this is how I think I do it:

this basically means that x1(3,4) + x2(-1, 1)+ x3(2, 0) = (0, 0)

so I set up the matrix

3 -1 2 = 0
4 1 0 = 0

I don't know why, but I have trouble solving this. the book says that the anser is

(3,4) -4(-1,1) - 7/2(2,0) = (0,0)

how?

 

[RaynorWolfcastle]

row reduction... if you can't figure this out, you suck at linear algebra.

 

[Semidevil]

well, I do suck at linear algerbra...

but anyways, row reduction on my calculator gives me


1 0 .29
0 1 -1.14

what do I do w/ that?

 

[silverpig]

#1: PUT DOWN THE DAMN CALCULATOR!!!

You can't do anything easily with those decimals.

Row reduce it by hand and you'll see what to do next.

 

[JetBlack69]

Originally posted by: silverpig
#1: PUT DOWN THE DAMN CALCULATOR!!!

 

[Spencer278]

Originally posted by: silverpig
#1: PUT DOWN THE DAMN CALCULATOR!!!

You can't do anything easily with those decimals.

Row reduce it by hand and you'll see what to do next.

Or get a better calculator that does fractions. But once you have the REF you solve the piviot variables in terms of the free variables then for any free variable in your range you can plug into your equations and get a linear combinations that equals zero.