My result doesn't agree with results from online calculators

Question

I'm doing an exercise about linear programming, but my answer doesn't agree with the answer from online calculators like this and this. Below is the problem statement: $$Minimize: u = 4x - 3y, s.t.$$ $$y \le -x + 1$$ $$y \le x + 1$$ $$y \ge 0$$

I found 3 corner: (-1,0), (0,1), (1,0) and min = -4 at (-1,0), but these calculators gives me the answer -3 at (0,1). Did I miss anything when solving this problem?

Your solution looks fine to me. BTW: you can use \leq to get $\leq$ and \geq to get $\geq$. — Dave, Dec 31 '18 at 01:22
Were you perhaps entering $x\geq 0$ as a constraint as well? — Dave, Dec 31 '18 at 01:24

score 2 · Accepted Answer · answered Dec 31 '18 at 01:26

2

The online calculators assume nonnegativity. If you write $x$ as the difference of two nonnegative numbers, your first calculator gives the right answer

Minimize p = 4x1-4x2-3y subject to
x1-x2+y <= 1
-x1+x2+y <= 1

answered Dec 31 '18 at 01:26

LinAlg

19,822

My result doesn't agree with results from online calculators

1 Answers1