Solve Equations 2x+3y-z=5,3x+2y+z=10,x-5y+3z=0 using Cramer's Rule method
Solution:
The equations can be expressed as
`2x+3y-z-5=0`
`3x+2y+z-10=0`
`x-5y+3z+0=0`
Use Cramer's Rule to find the values of x, y, z.
`(x)/D_x=(-y)/D_y=(z)/D_z=(-1)/D`
`D_x` | = | | `3` | `-1` | `-5` | | | `2` | `1` | `-10` | | | `-5` | `3` | `0` | |
|
`=3 xx (1 × 0 - (-10) × 3) +1 xx (2 × 0 - (-10) × (-5)) -5 xx (2 × 3 - 1 × (-5))`
`=3 xx (0 +30) +1 xx (0 -50) -5 xx (6 +5)`
`=3 xx (30) +1 xx (-50) -5 xx (11)`
`= 90 -50 -55`
`=-15`
`D_y` | = | | `2` | `-1` | `-5` | | | `3` | `1` | `-10` | | | `1` | `3` | `0` | |
|
`=2 xx (1 × 0 - (-10) × 3) +1 xx (3 × 0 - (-10) × 1) -5 xx (3 × 3 - 1 × 1)`
`=2 xx (0 +30) +1 xx (0 +10) -5 xx (9 -1)`
`=2 xx (30) +1 xx (10) -5 xx (8)`
`= 60 +10 -40`
`=30`
`D_z` | = | | `2` | `3` | `-5` | | | `3` | `2` | `-10` | | | `1` | `-5` | `0` | |
|
`=2 xx (2 × 0 - (-10) × (-5)) -3 xx (3 × 0 - (-10) × 1) -5 xx (3 × (-5) - 2 × 1)`
`=2 xx (0 -50) -3 xx (0 +10) -5 xx (-15 -2)`
`=2 xx (-50) -3 xx (10) -5 xx (-17)`
`= -100 -30 +85`
`=-45`
`D` | = | | `2` | `3` | `-1` | | | `3` | `2` | `1` | | | `1` | `-5` | `3` | |
|
`=2 xx (2 × 3 - 1 × (-5)) -3 xx (3 × 3 - 1 × 1) -1 xx (3 × (-5) - 2 × 1)`
`=2 xx (6 +5) -3 xx (9 -1) -1 xx (-15 -2)`
`=2 xx (11) -3 xx (8) -1 xx (-17)`
`= 22 -24 +17`
`=15`
`(x)/D_x=(-y)/D_y=(z)/D_z=(-1)/D`
`:.(x)/-15=(-y)/30=(z)/-45=(-1)/15`
`:.(x)/-15=(-1)/15,(-y)/30=(-1)/15,(z)/-45=(-1)/15`
`:.x=(15)/(15),y=(30)/(15),z=(45)/(15)`
`:.x=1,y=2,z=3`
This material is intended as a summary. Use your textbook for detail explanation.
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