document.write( "Question 1186115: The line 3kx + 8y = 5 is perpendicular to the line 6y - 4kx = -1. Find k. \n" ); document.write( "
Algebra.Com's Answer #816980 by MathLover1(20850)\"\" \"About 
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\n" ); document.write( "The line \"3kx+%2B+8y+=+5\" is perpendicular to the line \"6y+-+4kx+=+-1\".\r
\n" ); document.write( "\n" ); document.write( " Find \"k\".\r
\n" ); document.write( "\n" ); document.write( "write both lines in slope intercept form:\r
\n" ); document.write( "\n" ); document.write( "\"3kx+%2B+8y+=+5\"\r
\n" ); document.write( "\n" ); document.write( "\"8y+=+-3kx++%2B5\"\r
\n" ); document.write( "\n" ); document.write( "\"y+=+-%283k%2F8%29x++%2B5%2F8\"=> a slope is \"m1=-%283k%2F8%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"6y+-+4kx+=+-1\"\r
\n" ); document.write( "\n" ); document.write( "\"6y+=4kx+-1\"\r
\n" ); document.write( "\n" ); document.write( "\"y+=%284k%2F6%29x+-1%2F6\"\r
\n" ); document.write( "\n" ); document.write( "\"y+=%282k%2F3%29x+-1%2F6\"=> a slope is \"m2=%282k%2F3%29\"\r
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\n" ); document.write( "\n" ); document.write( "recall that perpendicular lines have a slopes negative reciprocal to each other\r
\n" ); document.write( "\n" ); document.write( "so, \"m2=-1%2Fm1\"\r
\n" ); document.write( "\n" ); document.write( "then\r
\n" ); document.write( "\n" ); document.write( "\"%282k%2F3%29=-1%2F%28-3k%2F8%29\"\r
\n" ); document.write( "\n" ); document.write( "\"%282k%2F3%29=1%2F%283k%2F8%29\".......cross multiply\r
\n" ); document.write( "\n" ); document.write( "\"2k%283k%2F8%29=1%2A3\"\r
\n" ); document.write( "\n" ); document.write( "\"k%283k%2F4%29=3\"\r
\n" ); document.write( "\n" ); document.write( "\"%283k%5E2%29%2F4=3\"\r
\n" ); document.write( "\n" ); document.write( "\"3k%5E2=3%2A4\"...simplify\r
\n" ); document.write( "\n" ); document.write( "\"k%5E2=4\"\r
\n" ); document.write( "\n" ); document.write( "\"k=sqrt%284%29\" \r
\n" ); document.write( "\n" ); document.write( "=> \"k=2\" or \"k=-2\"\r
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\n" ); document.write( "\n" ); document.write( "then, your lines are:\r
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\n" ); document.write( "\n" ); document.write( "\"y+=+-%28%283%2A2%29%2F8%29x++%2B5%2F8\"\r
\n" ); document.write( "\n" ); document.write( "\"y+=+-%283%2F4%29x++%2B5%2F8\"\r
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\n" ); document.write( "\n" ); document.write( "\"y+=%28%282%2A2%29%2F3%29x+-1%2F6\"\r
\n" ); document.write( "\n" ); document.write( "\"y+=%284%2F3%29x+-1%2F6\"\r
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\n" ); document.write( "\n" ); document.write( "or\r
\n" ); document.write( "\n" ); document.write( "\"y+=+-%28%283%2A-2%29%2F8%29x++%2B5%2F8\"\r
\n" ); document.write( "\n" ); document.write( "\"y+=+%283%2F4%29x++%2B5%2F8\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"y+=%28%282%2A-2%29%2F3%29x+-1%2F6\"\r
\n" ); document.write( "\n" ); document.write( "\"y+=-%284%2F3%29x+-1%2F6\"\r
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\n" ); document.write( "\n" ); document.write( "or\r
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