DRWLS CAN YOU ANSWER

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How do i solve inequalitites with three variables. I still can't figure it outplease help.

x+y=1
y-z=-3
2x+3y+z=1


THE ANSWERS ARE3,-2,1 HOW DID THEY GET THAT ANSWER.


This can be solved a number of ways.
1) subsitition
2) determinants
3) matricies.

Substution:
x= 1-y
y= z+3 or x= 1-z-3

In the third equation , put those two things for x, and y.
2x+3y+z=1
then solve for z. Then go back and solve for x and y.


I've done that already such as
the book states the following
that the answer is -x-y=-1
how did they get there after adding equation 2 and three


Substitute x = 1-y and z = y+3 in the third equation. Then you get an equation in y only:
2(1-y) + 3y + (y+3) = 1
2y + 5 = 1
y = -2
Then use the equations for x and z again.
x = 1-(-2) = 3 etc.

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