SOLUTION: Hi! I'm stumped on this last question on my homework. It's substitution and for some reason i can't figure it out and i kepe getting different answers for the variables. Could you

Algebra ->  Expressions-with-variables -> SOLUTION: Hi! I'm stumped on this last question on my homework. It's substitution and for some reason i can't figure it out and i kepe getting different answers for the variables. Could you       Log On


   

Question 104174: Hi! I'm stumped on this last question on my homework. It's substitution and for some reason i can't figure it out and i kepe getting different answers for the variables. Could you help me please? I don't think i can figure this one out.
x+y+3z=-4
-x-y-2z=5
2x-z=-3
thanks!!!
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
solving for y in the first equation gives y=-4-x-3z

substituting into the second equation gives -x-(-4-x-3z)-2z=5 ... -x+4+x+3z-2z=5 ... 4+z=5 ... z=1

substituting into the third equation gives 2x-(1)=-3 ... 2x=-2 ... x=-1

substituting back to the first equation gives -1+y+3(1)=-4 ... y+2=-4 ... y=-6