<h3>Answer:</h3>
(5, -2, -3)
<h3>Explanation:</h3>We assume your equations are ...
- x +3y -z = 2
- 4x +2y +5z = 1
- 3x +0y +z = 12
These have solution (x, y, z) = (5, -2, -3).
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<em>How we know</em>
Trying the choices in the last equation eliminates the first and last. Trying the second choice in the first equation eliminates it, leaving the 3rd choice as the answer you're looking for.
We also know because we can ask a graphing calculator to solve the matrix equation (or row-reduce the augmented matrix).
<em>Comment on this problem</em>
The hardest part of this problem is figuring your intent. The equations are not well-separated, so we have a hard time telling what is a constant and what is a coefficient. It took a couple of guesses to sort it out. A little editing before posting would be helpful.
