Answer:
[tex] - x + 5y - 10z = - 8 \\ 2x - y + 10z = 6 \\ \\ add \: (1) \: and \: (2) \\ x + 4y = - 2 \: (4) \\ add \: (2) \: and \: (3) \\ 2x - y + 10z = 6 \\ - 7x - 3y - 10z = 4 \\ - 5x - 4y = 10 \: (5) \\ add \: (4) \: and \: (5) \\ - 4x = 8 \\ \therefore \: x = - 2 \\ sub \: x \: in \: (4)\\ \: - 2 + 4y = - 2 \\ \therefore \: y = 0 \\ sub \: x \: and \: y \: in \: (3) \\ 2( - 2) - (0) + 10z = 6 \\ \therefore \: z = 1[/tex]
You may also use matrices to solve this problem that would be much faster...
