Question 365371
1.{{{x-y+z=8}}}
2.{{{x+y+z=6}}}
3.{{{x+y-z=-12}}}
Add eq. 1 and eq. 3,
{{{x-y+z+x+y-z=8-12}}}
{{{2x=-4}}}
{{{highlight(x=-2)}}}
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Add eq. 1 and eq. 2,
{{{x-y+z+x+y+z=8+6}}}
{{{2x+2z=14}}}
{{{2(-2)+2z=14}}}
{{{2z=18}}}
{{{highlight(z=9)}}}
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Then from eq. 2,
{{{x+y+z=6}}}
{{{-2+y+9=6}}}
{{{highlight(y=-1)}}}