Wednesday, February 24, 2016

`2x - 2y - 6z = -4, -3x + 2y + 6z = 1, x - y - 5z = -3` Solve the system of linear equations and check any solutions algebraically.

EQ1:   `2x-2y-6z=-4`

EQ2:   `-3x + 2y + 6z=1`


EQ3:    `x-y-5z=-3`


To solve this system of equation, let's apply elimination method. In this method, a variable or variables should be removed in order to get the value of the other variable.


Let's eliminate y. To do so, add EQ1 and EQ2.


           `2x-2y-6z=-4`


`+`      `-3x+2y+6z=1`


`----------------`


` `


                            `-x = -3`


Then, solve for x.


`(-x)/(-1)=(-3)/(-1)`


`x=3`


Isolate y again.Consider EQ1 and EQ3.


`2x-2y-6z=-4`


`x-y-5z=-3`


To be able to eliminate y, multiply EQ3 by -2. Then, add the two equations.


        `2x-2y-6z=-4`


`+` `-2x+2y+10z=6`


`---------------`


                         `4z=2`


And, solve for z.


`(4z)/4=2/4`


`z=1/2`


Now that the values of the two variables are known, let's solve for the remaining variable. Let's plug-in x=3 and z=1/2 to EQ1.


`2x - 2y -6z = -4`


`2(3)-2y-6(1/2)=-4`


`6-2y-3=-4`


`3-2y=-4`


`3-3-2y=-4-3`


`-2y=-7`


(-2y)/(-2)=(-7)/(-2)


`y=7/2`


Therefore, the solution is  `(3, 7/2, 1/2)` .

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