document.write( "Question 922400: For what value(s) of k will the lines
\n" ); document.write( "kx+5y=2 and 2x+(k+3)y=4 be:\r
\n" ); document.write( "\n" ); document.write( "a) parallel to each other? b)perpendicular to each other
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Algebra.Com's Answer #559561 by ankor@dixie-net.com(22740)\"\" \"About 
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For what value(s) of k will the lines
\n" ); document.write( "kx+5y=2 and 2x+(k+3)y=4 be: a) parallel to each other?
\n" ); document.write( ":
\n" ); document.write( "put both equations in the slope intercept form
\n" ); document.write( "kx + 5y = 2
\n" ); document.write( "5y = -kx + 2
\n" ); document.write( "y = \"-k%2F5\"x + \"2%2F5\"
\n" ); document.write( "and
\n" ); document.write( "2x + (k+3)y = 4
\n" ); document.write( "(k+3)y = -2x + 4
\n" ); document.write( "y = \"-2%2F%28%28k%2B3%29%29\"x + \"4%2F%28%28k%2B3%29%29\"
\n" ); document.write( "the slope of parallel lines are equal; therefore\
\n" ); document.write( "\"-k%2F5\" = \"-2%2F%28%28K%2B3%29%29\"
\n" ); document.write( "cross multiply
\n" ); document.write( "-k(k+3) = 5 * -2
\n" ); document.write( "-k(k+3) = -10
\n" ); document.write( "multiply both sides by -1
\n" ); document.write( "k(k+3) = 10
\n" ); document.write( "k^2 + 3k - 10 = 0
\n" ); document.write( "factors to
\n" ); document.write( "(k+5)(k-2) = 0
\n" ); document.write( "the positive solution
\n" ); document.write( "k = 2
\n" ); document.write( "the negative solution will also work
\n" ); document.write( "k = -5
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\n" ); document.write( "b)perpendicular to each other
\n" ); document.write( "the relationship of slopes of perpendicular lines: m1 * m2 = -1, therefore
\n" ); document.write( "\"-k%2F5\" * \"-2%2F%28%28k%2B3%29%29\" = -1
\n" ); document.write( "\"%282k%29%2F%285%28k%2B3%29%29\" = -1
\n" ); document.write( "\"%282k%29%2F%28%285k%2B15%29%29\" = -1
\n" ); document.write( "2k = -1(5k+15)
\n" ); document.write( "2k = -5k - 15
\n" ); document.write( "2k + 5k = -15
\n" ); document.write( "7k = -15
\n" ); document.write( "k = \"-15%2F7\" value for perpendicular lines
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