2x-y+3z=-12, -x+2y-3z=15|, y+5z=-6

asked Jan 3 in Algebra 1 Answers by Liz

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From 3rd equation: y=-6-5z. Substitute for y in other two equations:

2x+6+5z+3z=-12; 2x+8z=-18; (A) x+4z=-9.

-x-12-10z-3z=15; (B) -x-13z=27.

Add A and B: -9z=18, z=-2; so x=-9-4z=-1 and y=-6-5z=4.

CHECK:

-2-4-6=-12 OK; 1+8+6=15 OK; 4-10=-6 OK

So solution is x=-1, y=4, z=-2.

answered Jan 3 by Rod Top Rated User (442,380 points)

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