SOLUTION: What is the value of x in the solution to the system if equations. x + 2y + 4z = 12 y + 2z = 8 5y = 10

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Question 440021: What is the value of x in the solution to the system if equations.
x + 2y + 4z = 12
y + 2z = 8
5y = 10
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
(1) +x+%2B+2y+%2B+4z+=+12+
(2) +y+%2B+2z+=+8+
(3) +5y+=+10+
There are 3 equations and 3 unknowns, so it's solvable
(2) +y+%2B+2z+=+8+
(2) +2z+=+-y+%2B+8+
(2) +z+=+%28-1%2F2%29%2Ay+%2B+4+
Substitute this into (1)
(1) +x+%2B+2y+%2B+4%2A%28%28-1%2F2%29%2Ay+%2B+4%29+=+12+
(1) +x+%2B+2y+-+2y+%2B+16+=+12+
(1) +x+=+-4+
and
(3) +5y+=+10+
(3) +y+=+2+
and
(2) +z+=+%28-1%2F2%29%2Ay+%2B+4+
(2) +z+=+%28-1%2F2%29%2A2+%2B+4+
(2) +z+=+-1+%2B+4+
(2) +z+=+3+