Question 364623
First graph the line,{{{2x-y=12}}}
{{{y=2x-12}}}
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{{{graph(300,300,-10,10,-10,10,2x-12)}}}
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Now choose a point not on the line. 
({{{0}}},{{{0}}}) is a convenient choice.
Test the inequality.
If the inequality is satisfied, shade the region containing ({{{0}}},{{{0}}}).
If not, shade the region that does not contain ({{{0}}},{{{0}}}).
{{{2x-y>=12}}}
{{{2(0)-0>=12}}}
{{{0>=12}}}
False, shade the region not containing ({{{0}}},{{{0}}})
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*[invoke plot_any_inequality "2x-y>=12", -10, 10, -10, 10, 300, 300]