SOLUTION: I need help solving this problem using the Gaussian Elimination method step by step please! 4x+3y+2z=6 -2x-y+5z=5 x+2y-3z=3 thank you in advance!

Algebra ->  Matrices-and-determiminant -> SOLUTION: I need help solving this problem using the Gaussian Elimination method step by step please! 4x+3y+2z=6 -2x-y+5z=5 x+2y-3z=3 thank you in advance!       Log On


   



Question 148619: I need help solving this problem using the Gaussian Elimination method step by step please!
4x+3y+2z=6
-2x-y+5z=5
x+2y-3z=3
thank you in advance!

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
1.4x%2B3y%2B2z=6
2.-2x-y%2B5z=5
3.x%2B2y-3z=3
Combine equations to remove one of the variables.
Multiply eq. 2 by (3) and add to eq. 1,
2.3%28-2x-y%2B5z%29=3%285%29
2.-6x-3y%2B15z=15
This gets rid of y and makes a new eq. 1 with just x and z,
1.4x%2B3y%2B2z-6x-3y%2B15z=6%2B15
1.-2x%2B17z=21
Multiply eq. 2 by (2) and add to eq. 3,
2.2%28-2x-y%2B5z%29=2%285%29
2.-4x-2y%2B10z%29=10
This gets rid of y and makes a new eq. 3 with just x and z,
3.x%2B2y-3z-4x-2y%2B10z=3%2B10
3.-3x%2B7z=13
Now we have two equations in x and z.
1.-2x%2B17z=21
3.-3x%2B7z=13
We can continue to reduce to one variable.
Multiply eq. 1 by 3 and eq. 3 by -2 and add them to get rid of x,
1.3%28-2x%2B17z%29=3%2821%29
1.-6x%2B51z=63
3.-2%28-3x%2B7z%29=-2%2813%29
3.6x-14z=-26
Now add the two eqs.
-6x%2B51z%2B6x-14z=63-26
37z=37
z=1
Now that you have z, work backwards and back substitute to find x and then y.
You can use any of the previous equations to solve for other variables.
-3x%2B7z=13
-3x%2B7%281%29=13
-3x%2B7=13
-3x=6
x=-2
And finally for y,
2.-2x-y%2B5z=5
-2%28-2%29-y%2B5%281%29=5
4-y%2B5=5
y=4
(x,y,z)=(-2,4,1)