document.write( "Question 318876: If the graph of the equation ax+3y=9 is perpendicular to the graph of the equation 3x+y=-4, find the value of a \n" ); document.write( "

Algebra.Com's Answer #228262 by Fombitz(32388) $\"\"$ $\"About$

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Convert both equations to slope-intercept form,
\n" ); document.write( " $\"ax%2B3y=9\"$
\n" ); document.write( " $\"3y=-ax%2B9\"$
\n" ); document.write( " $\"y=-%28a%2F3%29x%2B3\"$
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\n" ); document.write( " $\"3x%2By=-4\"$
\n" ); document.write( " $\"y=-3x-4\"$
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\n" ); document.write( "Perpendicular lines have slopes that are negative reciprocals,
\n" ); document.write( " $\"m1%2Am2=-1\"$
\n" ); document.write( " $\"-%28a%2F3%29%2A%28-3%29=-1\"$
\n" ); document.write( " $\"highlight%28a=-1%29\"$
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