Question 512729
x = 3-3y
x +3y = -6
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rearrange the first equation
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x + 3y = 3
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Hmmm.  That's doesn't sound right.
x  + 3y = 3
and
x + 3y = -6
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Subtract the two equations and you'll find 0 = 9.
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But, we can look at these in slope-intercept form.
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x = 3-3y
3y +x = 3
3y = -x +3
y = -1/3x +1
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x +3y = -6
3y = -x -6
y = -1/3x -2
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Aha!  They're parallel lines, so there is no intersection.
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{{{graph(500,500,-10,10,-10,10,-1/3*x+1,-1/3*x-2)}}}