For some reason I can't see how:

x+3y-z = 1

-4y + 5z = 4

can become:

x = 2-11t

y =-1+5t

z=4t

Can someone explain the step/steps between?

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- November 28th 2005, 06:18 AMprime_66simple gauss elimination prob.
For some reason I can't see how:

x+3y-z = 1

-4y + 5z = 4

can become:

x = 2-11t

y =-1+5t

z=4t

Can someone explain the step/steps between? - November 28th 2005, 10:11 AMCaptainBlackQuote:

Originally Posted by**prime_66**

is an under-determined system, so there will be

a free parameter in any solution. So we choose

so that it maximises the convenience of solving

the system in terms of it.

The constant on the RHS of the second equation is , as is the

coefficient of on the LHS. So setting allows

us to divide through by , and solve for in terms of .

Having found and in terms of

we just substitute these into the first equation to solve for

in terms of .

RonL - November 28th 2005, 10:15 AMprime_66
thanx, I thought z had to be equal to just t. but now i understand :)