document.write( "Question 720029: Find the value of k so that the line containing the points (−7,−7) and (3,k) is perpendicular to the line y=−1/4x+1. \n" ); document.write( "

Algebra.Com's Answer #441625 by josmiceli(19441) $\"\"$ $\"About$

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Any line perpendicular to the line
\n" ); document.write( " $\"+y+=+mx+%2B+b+\"$
\n" ); document.write( "has a slope = $\"+-1%2Fm+\"$
\n" ); document.write( "In this case the slope is $\"+-1%2F4+\"$ , so
\n" ); document.write( " $\"+m+=+%28-1%29%2F%28+-1%2F4%29+\"$
\n" ); document.write( " $\"+m+=+4+\"$
\n" ); document.write( "Now I can use the point-slope formula
\n" ); document.write( " $\"+%28+k+-%28-7%29+%29+%2F+%28+3+-%28-7%29+%29+=+4+\"$
\n" ); document.write( " $\"+%28+k+%2B+7+%29+%2F+%28+3+%2B+7+%29+=+4+\"$
\n" ); document.write( " $\"+k+%2B+7+=+4%2A10+\"$
\n" ); document.write( " $\"+k+=+40+-+7+\"$
\n" ); document.write( " $\"+k+=+33+\"$ \r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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