Find solution using Simplex method (BigM method)
MAX Z = 22x1 + 6x2 + 2x3
subject to
10x1 + 2x2 + x3 <= 100
7x1 + 3x2 + 2x3 <= 72
2x1 + 4x2 + x3 <= 80
and x1,x2,x3 >= 0; Solution:Problem is | Max `Z` | `=` | `` | `22` | `x_1` | ` + ` | `6` | `x_2` | ` + ` | `2` | `x_3` |
|
| subject to |
| `` | `10` | `x_1` | ` + ` | `2` | `x_2` | ` + ` | `` | `x_3` | ≤ | `100` | | `` | `7` | `x_1` | ` + ` | `3` | `x_2` | ` + ` | `2` | `x_3` | ≤ | `72` | | `` | `2` | `x_1` | ` + ` | `4` | `x_2` | ` + ` | `` | `x_3` | ≤ | `80` |
|
| and `x_1,x_2,x_3 >= 0; ` |
The problem is converted to canonical form by adding slack, surplus and artificial variables as appropiate
1. As the constraint-1 is of type '`<=`' we should add slack variable `S_1`
2. As the constraint-2 is of type '`<=`' we should add slack variable `S_2`
3. As the constraint-3 is of type '`<=`' we should add slack variable `S_3`
After introducing slack variables| Max `Z` | `=` | `` | `22` | `x_1` | ` + ` | `6` | `x_2` | ` + ` | `2` | `x_3` | ` + ` | `0` | `S_1` | ` + ` | `0` | `S_2` | ` + ` | `0` | `S_3` |
|
| subject to |
| `` | `10` | `x_1` | ` + ` | `2` | `x_2` | ` + ` | `` | `x_3` | ` + ` | `` | `S_1` | | | | | | | = | `100` | | `` | `7` | `x_1` | ` + ` | `3` | `x_2` | ` + ` | `2` | `x_3` | | | | ` + ` | `` | `S_2` | | | | = | `72` | | `` | `2` | `x_1` | ` + ` | `4` | `x_2` | ` + ` | `` | `x_3` | | | | | | | ` + ` | `` | `S_3` | = | `80` |
|
| and `x_1,x_2,x_3,S_1,S_2,S_3 >= 0` |
| Tableau-1 | `C_j` | `22` | `6` | `2` | `0` | `0` | `0` | | |
| `C_B` | `"Basis"` | `x_1` | `x_2` | `x_3` | `S_1` | `S_2` | `S_3` | `RHS` | `"Ratio"=(RHS)/(x_1)` |
| `R_1` `0` | `S_1` | `(10)` | `2` | `1` | `1` | `0` | `0` | `100` | `(100)/(10)=10``->` |
| `R_2` `0` | `S_2` | `7` | `3` | `2` | `0` | `1` | `0` | `72` | `(72)/(7)=10.2857` |
| `R_3` `0` | `S_3` | `2` | `4` | `1` | `0` | `0` | `1` | `80` | `(80)/(2)=40` |
| | `Z_j` | `0` | `0` | `0` | `0` | `0` | `0` | `Z=0` | |
| | `Z_j-C_j` | `-22``uarr` | `-6` | `-2` | `0` | `0` | `0` | | |
Most Negative `Z_j-C_j` is `-22`. So,
the entering variable is `x_1`.
Minimum ratio is `10`. So,
the leaving basis variable is `S_1`.
`:.`
The pivot element is `10`.
Entering `=x_1`, Departing `=S_1`, Key Element `=10`
`R_1`(new)`= R_1`(old) `-: 10`
| `x_1` | `x_2` | `x_3` | `S_1` | `S_2` | `S_3` | `RHS` |
| `R_1`(old) = | `10` | `2` | `1` | `1` | `0` | `0` | `100` |
| `R_1`(new)`= R_1`(old) `-: 10` | `1` | `0.2` | `0.1` | `0.1` | `0` | `0` | `10` |
`R_2`(new)`= R_2`(old) - `7 R_1`(new)
| `x_1` | `x_2` | `x_3` | `S_1` | `S_2` | `S_3` | `RHS` |
| `R_2`(old) = | `7` | `3` | `2` | `0` | `1` | `0` | `72` |
| `R_1`(new) = | `1` | `0.2` | `0.1` | `0.1` | `0` | `0` | `10` |
| `7 xx R_1`(new) = | `7` | `1.4` | `0.7` | `0.7` | `0` | `0` | `70` |
| `R_2`(new)`= R_2`(old) - `7 R_1`(new) | `0` | `1.6` | `1.3` | `-0.7` | `1` | `0` | `2` |
`R_3`(new)`= R_3`(old) - `2 R_1`(new)
| `x_1` | `x_2` | `x_3` | `S_1` | `S_2` | `S_3` | `RHS` |
| `R_3`(old) = | `2` | `4` | `1` | `0` | `0` | `1` | `80` |
| `R_1`(new) = | `1` | `0.2` | `0.1` | `0.1` | `0` | `0` | `10` |
| `2 xx R_1`(new) = | `2` | `0.4` | `0.2` | `0.2` | `0` | `0` | `20` |
| `R_3`(new)`= R_3`(old) - `2 R_1`(new) | `0` | `3.6` | `0.8` | `-0.2` | `0` | `1` | `60` |
| Tableau-2 | `C_j` | `22` | `6` | `2` | `0` | `0` | `0` | | |
| `C_B` | `"Basis"` | `x_1` | `x_2` | `x_3` | `S_1` | `S_2` | `S_3` | `RHS` | `"Ratio"=(RHS)/(x_2)` |
| `R_1` `22` | `x_1` | `1` | `0.2` | `0.1` | `0.1` | `0` | `0` | `10` | `(10)/(0.2)=50` |
| `R_2` `0` | `S_2` | `0` | `(1.6)` | `1.3` | `-0.7` | `1` | `0` | `2` | `(2)/(1.6)=1.25``->` |
| `R_3` `0` | `S_3` | `0` | `3.6` | `0.8` | `-0.2` | `0` | `1` | `60` | `(60)/(3.6)=16.6667` |
| | `Z_j` | `22` | `4.4` | `2.2` | `2.2` | `0` | `0` | `Z=220` | |
| | `Z_j-C_j` | `0` | `-1.6``uarr` | `0.2` | `2.2` | `0` | `0` | | |
Most Negative `Z_j-C_j` is `-1.6`. So,
the entering variable is `x_2`.
Minimum ratio is `1.25`. So,
the leaving basis variable is `S_2`.
`:.`
The pivot element is `1.6`.
Entering `=x_2`, Departing `=S_2`, Key Element `=1.6`
`R_2`(new)`= R_2`(old) `-: 1.6`
| `x_1` | `x_2` | `x_3` | `S_1` | `S_2` | `S_3` | `RHS` |
| `R_2`(old) = | `0` | `1.6` | `1.3` | `-0.7` | `1` | `0` | `2` |
| `R_2`(new)`= R_2`(old) `-: 1.6` | `0` | `1` | `0.8125` | `-0.4375` | `0.625` | `0` | `1.25` |
`R_1`(new)`= R_1`(old) - `0.2 R_2`(new)
| `x_1` | `x_2` | `x_3` | `S_1` | `S_2` | `S_3` | `RHS` |
| `R_1`(old) = | `1` | `0.2` | `0.1` | `0.1` | `0` | `0` | `10` |
| `R_2`(new) = | `0` | `1` | `0.8125` | `-0.4375` | `0.625` | `0` | `1.25` |
| `0.2 xx R_2`(new) = | `0` | `0.2` | `0.1625` | `-0.0875` | `0.125` | `0` | `0.25` |
| `R_1`(new)`= R_1`(old) - `0.2 R_2`(new) | `1` | `0` | `-0.0625` | `0.1875` | `-0.125` | `0` | `9.75` |
`R_3`(new)`= R_3`(old) - `3.6 R_2`(new)
| `x_1` | `x_2` | `x_3` | `S_1` | `S_2` | `S_3` | `RHS` |
| `R_3`(old) = | `0` | `3.6` | `0.8` | `-0.2` | `0` | `1` | `60` |
| `R_2`(new) = | `0` | `1` | `0.8125` | `-0.4375` | `0.625` | `0` | `1.25` |
| `3.6 xx R_2`(new) = | `0` | `3.6` | `2.925` | `-1.575` | `2.25` | `0` | `4.5` |
| `R_3`(new)`= R_3`(old) - `3.6 R_2`(new) | `0` | `0` | `-2.125` | `1.375` | `-2.25` | `1` | `55.5` |
| Tableau-3 | `C_j` | `22` | `6` | `2` | `0` | `0` | `0` | | |
| `C_B` | `"Basis"` | `x_1` | `x_2` | `x_3` | `S_1` | `S_2` | `S_3` | `RHS` | `"Ratio"` |
| `R_1` `22` | `x_1` | `1` | `0` | `-0.0625` | `0.1875` | `-0.125` | `0` | `9.75` | |
| `R_2` `6` | `x_2` | `0` | `1` | `0.8125` | `-0.4375` | `0.625` | `0` | `1.25` | |
| `R_3` `0` | `S_3` | `0` | `0` | `-2.125` | `1.375` | `-2.25` | `1` | `55.5` | |
| | `Z_j` | `22` | `6` | `3.5` | `1.5` | `1` | `0` | `Z=222` | |
| | `Z_j-C_j` | `0` | `0` | `1.5` | `1.5` | `1` | `0` | | |
Since all `Z_j-C_j >= 0`
Hence, optimal solution is arrived with value of variables as :
`x_1=9.75,x_2=1.25,x_3=0`
Max `Z=222`
This material is intended as a summary. Use your textbook for detail explanation.
Any bug, improvement, feedback then