SOLUTION: 2x+y-z=20 X+3y=13 X=3

Click here to see ALL problems on Systems-of-equations

Question 1091559: 2x+y-z=20
X+3y=13
X=3
Found 3 solutions by josgarithmetic, MathTherapy, ikleyn:
Answer by josgarithmetic(39628)   (Show Source):
You can put this solution on YOUR website!
---------------------
2x+y-z=20
x+3y=13
x=3
--------------------

----------------
6+y-z=20
3+3y=13
---------------

---------------
y-z=14
3y=10
--------------
.
How about now?

Answer by MathTherapy(10556)   (Show Source):
You can put this solution on YOUR website!

2x+y-z=20
X+3y=13
X=3

He is WRONG, WRONG, WRONG, as usual.

Answer by ikleyn(52865)   (Show Source):
You can put this solution on YOUR website!
.
The correct solution is THIS:

2x + y - z = 20 (1) x + 3y = 13 (2) x = 3 (3) The equation (3) just gives you the solution for x: x = 3. Substitute it into equation (2). You will get 3 + 3y = 13 ====> 3y = 13 - 3 = 10 ===> y = = . Thus you found the unknown y, too. Now substitute x = 3, y = into equation (1). You will get = 20 ====> z = = - = . Answer. x = 3, y = , z = .

Solved.

Ignore writing by @josgarithmetic, because it leads you in wrong direction.