# Linear Programing Problem, Simplex but with a negative constraint?

• Mar 6th 2012, 03:17 AM
Stylis10
[SOLVED] Linear Programing Problem, Simplex but with a negative constraint?
Hi, I have the following question and I need to know if i have augmented it correctly and what my next steps should be.

Maximise
$Z = x_{1} + 4x_{2}$
subject to
$-3x_{1} + x_{2} \leq 6$
$x_{1} + 2x_{2} \leq 4$
and $x_{2} \geq -3$

My steps to solve were

let $x'_{2} = x_{2} + 3$

so then we have:
$Z = x_{1} + 4x'_{2} -12$
$-3x_{1} + x'_{2} \leq 9$
$x_{1} + 2x'_{2} \leq 10$
and $x'_{2} \geq 0$

i thought this was the correct augmented form of the LPP, however, none of the multiple choice answers i can choose from show this, hence i know it is wrong, but I'm not sure what i have done wrong, all the answers have added more variables.
• Mar 6th 2012, 04:29 AM
Stylis10
Re: Linear Programing Problem, Simplex but with a negative constraint?
I have come up with this as my augmented problem:

$Z = x^+_{1} - x^-_{1} + 4x'_{2} -12$
$-3x^+_{1} + 3x^-_{1} + x'_{2} + x_{3} = 9$
$x^+_{1} - x^-_{1} + 2x'_{2} + x_{4} = 10$
$x^+_{1} \geq 0, x^-_{1} \geq 0, x'_{2} \geq 0, x_{3} \geq 0, x_{4} \geq 0$

However, when i try to solve this in a tableau i don't get any of the answers given.
Am i first supposed to change the first equation so that $x^+_{1}, x^-_{1}$ and $x'_{2}$ coefficients are to equal zero or just some of the variables.
• Mar 6th 2012, 05:36 AM
Stylis10
Re: Linear Programing Problem, Simplex but with a negative constraint?
Solved