Question 445237: I believe this topic explains it best, i need to solve the system using the elimination method. I have tried several times, and I feel like there is no solution; although my instructor said there is.
2w+x+y+2z=-2
3w+2x+y-z=9
w+x+y+z=0
w+2x+2y-z=10
Thanks!
Answer by AnlytcPhil(1806) (Show Source):
You can put this solution on YOUR website! I believe this topic explains it best, i need to solve the system using the elimination method. I have tried several times, and I feel like there is no solution; although my instructor said there is.
That's 4 equations in 4 variables
2w + x + y + 2z = -2
3w + 2x + y - z = 9
w + x + y + z = 0
w + 2x + 2y - z = 10
First we get it down to 3 equations in 3 variables
by choosing a variable to eliminate, and eliminating
it from 3 pairs of equations making sure all 4 equations
are used. I will choose z to eliminate.
We eliminate z from the first two equations by
multiplying the 2nd eq. by 2 and adding to the 1st:
2w + x + y + 2z = -2
6w + 4x + 2y - 2z = 18
----------------------
8w + 5x + 3y = 16
We eliminate z from the 2nd & 3rd equations by
just adding them as they are:
3w + 2x + y - z = 9
w + x + y + z = 0
----------------------
4w + 3x + 2y = 9
We eliminate z from the 3rd & 4th equations by
just adding them as they are:
w + x + y + z = 0
w + 2x + 2y - z = 10
----------------------
2w + 3x + 3y = 10
Now we have it down to 3 equations in 3 variables.
8w + 5x + 3y = 16
4w + 3x + 2y = 9
2w + 3x + 3y = 10
Next we get it down to 2 equations in 2 variables
by choosing a variable to eliminate, and eliminating
it from 2 pairs of equations, making sure that all
3 equations are used. I choose w to eliminate:
We eliminate w from the 2nd & 3rd equations by multiplying
the second equation by -2 and adding it to the 1st equation:
8w + 5x + 3y = 16
-8w - 6x - 4y = -18
-------------------
-x - y = -2
We eliminate w from the first two equations by multiplying
the 3rd equation by -2 and adding it to the 2nd equation:
4w + 3x + 2y = 9
-4w - 6x - 6y = -20
-------------------
-3x - 4y = -11
Now we have it down to 2 equations in 2 variables.
-x - y = -2
-3x - 4y = -11
Next we get it down to 1 equation in 1 variables
by choosing a variable to eliminate. I choose y
to eliminate:
We eliminate y by multiplying the 1st equation by -4
and adding the 2nd equation to it:
4x + 4y = 8
-3x - 4y = -11
----------------
x = -3
That's 1 equation in 1 variable solved. So we
substitute in
-x - y = -2
-(-3) - y = -2
3 - y = -2
-y = -5
y = 5
Then we substitute x = -3 and y = 5 in
2w + 3x + 3y = 10
2w + 3(-3) + 3(5) = 10
2w - 9 + 15 = 10
2w + 6 = 10
2w = 4
w = 2
Then we substitute x = -3 and y = 5 and w = 2 in
w + x + y + z = 0
2 + (-3) + 5 + z = 0
4 + z = 0
z = -4
So (w,x,y,z) = (2,-3,5,-4)
Edwin
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