document.write( "Question 895054: Tom can run 5 miles in 1 hour less than the time required for David to run 4 miles. If tom is 4 mph faster than David, how many hours does each man run? \n" ); document.write( "

Algebra.Com's Answer #542565 by lwsshak3(11628) $\"\"$ $\"About$

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Tom can run 5 miles in 1 hour less than the time required for David to run 4 miles. If tom is 4 mph faster than David, how many hours does each man run?
\n" ); document.write( "***
\n" ); document.write( "let x=David's speed
\n" ); document.write( "x+4=Tom's speed
\n" ); document.write( "Travel time=Distance/speed
\n" ); document.write( "..
\n" ); document.write( "(4/x)-5/(x+4))=1
\n" ); document.write( "lcd:x(x+4)
\n" ); document.write( "4(x+4)-5x=x(x+4)
\n" ); document.write( "4x+16-5x=x^2+4x
\n" ); document.write( "x^2+5x-16
\n" ); document.write( "solve for x by quadratic formula:
\n" ); document.write( " $\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"$
\n" ); document.write( "a=1, b=-5, c=-16
\n" ); document.write( "ans:
\n" ); document.write( "x≈-7.2 (reject)
\n" ); document.write( "or
\n" ); document.write( "x≈2.2
\n" ); document.write( "x+4≈6.2
\n" ); document.write( "..
\n" ); document.write( "4/2.2≈1.8 hrs
\n" ); document.write( "5/6.2≈0.8 hrs
\n" ); document.write( "how many hours does each man run?
\n" ); document.write( "Tom:0.8
\n" ); document.write( "David:1.8\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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