document.write( "Question 384497: The algebraic relation d=0.0056s^2+0.14s models the relation between a vehicle's stopping distance d, in meters, and its speed s, in kilometers per hour. What is the fastest you could drive and still be able to stop within 80m? What is the stopping distance for a car travelling at 120km/h? Estimate the length of an average car. How many cars lengths does the stopping distance in (b) correspond to? \n" ); document.write( "
Algebra.Com's Answer #272184 by nerdybill(7384)\"\" \"About 
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The algebraic relation d=0.0056s^2+0.14s models the relation between a vehicle's stopping distance d, in meters, and its speed s, in kilometers per hour. What is the fastest you could drive and still be able to stop within 80m?
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\n" ); document.write( "Set d to 80m and solve for s:
\n" ); document.write( "d=0.0056s^2+0.14s
\n" ); document.write( "80=0.0056s^2+0.14s
\n" ); document.write( "0=0.0056s^2+0.14s-80
\n" ); document.write( "Solving using the quadratic formula yields:
\n" ); document.write( "x = {113.26, -141.26}
\n" ); document.write( "throw out the negative answer leaving
\n" ); document.write( "x = 113.26 km/hour
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\n" ); document.write( "What is the stopping distance for a car travelling at 120km/h?
\n" ); document.write( "set x to 120 and solve for d:
\n" ); document.write( "d=0.0056s^2+0.14s
\n" ); document.write( "d=0.0056(120)^2+0.14(120)
\n" ); document.write( "d = 97.44 m
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\n" ); document.write( "Estimate the length of an average car. How many cars lengths does the stopping distance in (b) correspond to?
\n" ); document.write( "Assuming the avg length of a car is 4 meters
\n" ); document.write( "then
\n" ); document.write( "97.44/4 = 24.36 = 24 car lengths \n" ); document.write( "
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