Question 1021683
Original equation:
x-3y=5
x-5=3y
(1/3)x-(5/3)=y
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y=(1/3)x-(5/3) (RED line on graph)
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The slope of the original line is 1/3, 
so the slope of the perpendicular line would be -3.
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Use x=0 and y=6 to find b.
y=mx+b
y=-3x+b
6=-3(0)+b
6=b
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ANSWER: The equation is y=-3x+6 (GREEN line on graph)
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GRAPH:
{{{ graph( 800, 800, -10, 10, -10, 10, (1/3)x+(5/3), -3x+6) }}}