[Oops.]Wrong notation

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**Chapter number or note title:** [H.2 The Geometry of Linear Programming]

**Page number:** [3]

**Error description:** [For each variable x_j, add two new variables x_**i**^+ and x_**i**^-...]

**Suggested fix (if any):** [For each variable x_j, add two new variables x_j^+ and x_j^-...]
