document.write( "Question 1029727: Chris went on a bike ride of 24 miles. He realized that if he had gone 6 mph faster, he would have arrived 9 hours sooner. How fast did he actually ride? \n" ); document.write( "
Algebra.Com's Answer #644774 by Theo(13342)![]() ![]() You can put this solution on YOUR website! rt = d \n" ); document.write( "d = 24 \n" ); document.write( "rt = 24\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(r+6)(t-9) = 24 \n" ); document.write( "simplify to get rt - 9r + 6t - 54 = 24\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "rt = 24 \n" ); document.write( "solve for r to get r = 24/t\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "replace r with 24/t in the equation of rt - 9r + 6t - 54 = 24 to get: \n" ); document.write( "24t/t - 216/t + 6t - 54 = 24\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "multiply both sides of this equation by t to get: \n" ); document.write( "24t - 216 + 6t^2 - 54t = 24t\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "subtract 24t from both sides of this equation and combine like terms and reorder the terms in descending order of degree to get: \n" ); document.write( "6t^2 - 54t - 216 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "factor out the gcf of 6 to get: \n" ); document.write( "t^2 - 9t - 36 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "factor this quadratic equation to get: \n" ); document.write( "(t-12)(t+3)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "solve for t to get: \n" ); document.write( "t = 12 or t = -3 \n" ); document.write( "t = -3 can't be good because time is not negative, so you get t = 12.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "when t = 12, rt = 24 becomes r*12 = 24 and solve for r to get r = 2.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you have r = 2 \n" ); document.write( "t = 12\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "rt = d becomes 2*12 = 24, confirming this is good.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "r+6 = 8 \n" ); document.write( "t-9 = 3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(r+6)(t-9) = d becomes 8*3 = 24, confirming this is also good.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your solution is that he was riding at 2 miles per hour.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |