document.write( "Question 467974: The formula r=2sqrt(5l) can be used to approximate the speed r, in miles per hour, of a car that has left skid marks of length l, in feet. How far will a car skid at 60 mph?
\n" ); document.write( "The car will skid ? feet
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Algebra.Com's Answer #321170 by Theo(13342)\"\" \"About 
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the formula is r = 2 * sqrt (5*l)
\n" ); document.write( "r = speed
\n" ); document.write( "l = number of feet of skid.
\n" ); document.write( "if the car is traveling at 60 miles per hour, then the equation becomes:
\n" ); document.write( "60 = 2 * sqrt (5*l)
\n" ); document.write( "you want to solve for l.
\n" ); document.write( "divide both sides of this equation by 2 to get:
\n" ); document.write( "30 = sqrt(5*l)
\n" ); document.write( "square both sides of this equation to get:
\n" ); document.write( "30^2 = (sqrt(5*l))^2 which becomes:
\n" ); document.write( "900 = 5*l
\n" ); document.write( "divide both sides of this equation by 5 to get:
\n" ); document.write( "180 = l
\n" ); document.write( "this means that the car will skid 180 feet.
\n" ); document.write( "to confirm this is a good answer, replace r with 60 and l with 180 in the original equation to get:
\n" ); document.write( "r = 2 * sqrt(5*l) becomes:
\n" ); document.write( "60 = 2 * sqrt(5*180) which becomes:
\n" ); document.write( "60 = 2 * sqrt(900) which becomes:
\n" ); document.write( "60 = 2 * 30 which becomes:
\n" ); document.write( "60 = 60
\n" ); document.write( "since the equation is true, then the answer of l = 180 is confirmed as good.
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