document.write( "Question 156304: Given two lines whose equations are 3x+y-8 =0 and -2x+by+9 =0, determine the value of b such that the two lines will be perpendicular.
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Algebra.Com's Answer #115108 by nerdybill(7384)\"\" \"About 
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3x+y-8 =0 and -2x+by+9 =0
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\n" ); document.write( "Start by determining the slope of
\n" ); document.write( "3x+y-8 =0
\n" ); document.write( "Do this by manipulating it into the \"slope-intercept\" form:
\n" ); document.write( "y = mx + b
\n" ); document.write( "where
\n" ); document.write( "m is the slope
\n" ); document.write( "b is the y-intercept at (0,b)
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\n" ); document.write( "3x+y-8 =0
\n" ); document.write( "y-8 = -3x
\n" ); document.write( "y = -3x + 8
\n" ); document.write( "So, the slope is -3
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\n" ); document.write( "Next, manipulate the other equation into the same form:
\n" ); document.write( "-2x+by+9 =0
\n" ); document.write( "by+9 =2x
\n" ); document.write( "by = 2x - 9
\n" ); document.write( "y = (2/b)x -9/b
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\n" ); document.write( "For two lines to be perpendicular, the slopes must be negative reciprocal.
\n" ); document.write( "slope of first equation: -3
\n" ); document.write( "slope of second equation: 2/b
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\n" ); document.write( "-3(2/b) = -1
\n" ); document.write( "3(2/b) = 1
\n" ); document.write( "3(2) = b
\n" ); document.write( "6 = b
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