document.write( "Question 665081: two cars leave an intersection, one traveling west and the other south. After some time the faster car is 3 mi farther away from the intersection than the slower car. At the time the two cars where 15 miles apart.
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document.write( " How far did each car travel?
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Algebra.Com's Answer #413760 by ankor@dixie-net.com(22740)![]() ![]() You can put this solution on YOUR website! two cars leave an intersection, one traveling west and the other south. \n" ); document.write( " After some time the faster car is 3 mi farther away from the intersection than the slower car. \n" ); document.write( " At the time the two cars where 15 miles apart. How far did each car travel? \n" ); document.write( ": \n" ); document.write( "Let d = distance traveled by the 1st car when they were 15 mi apart \n" ); document.write( "then \n" ); document.write( "(d+3) = distance traveled by the faster car \n" ); document.write( ": \n" ); document.write( "This is pythag problem: a^2 + b^2 = c^2, where \n" ); document.write( "a = d \n" ); document.write( "b = (d+3) \n" ); document.write( "c = 15 \n" ); document.write( ": \n" ); document.write( "d^2 + (d+3)^2 = 15^2 \n" ); document.write( "FOIL(d+3)(d+3) \n" ); document.write( "d^2 + d^2 + 3d + 3d + 9 = 225 \n" ); document.write( ": \n" ); document.write( "2d^2 + 6d + 9 - 225 = 0 \n" ); document.write( "2d^2 + 6d - 216 = 0 \n" ); document.write( "simplify, divide by 2 \n" ); document.write( "d^2 + 3d - 108 = 0 \n" ); document.write( "this will factor to \n" ); document.write( "(d+12)(d-9) = 0 \n" ); document.write( "the positive solution is all we want here \n" ); document.write( "d = 9 mi, and 12 mi when they were 15 mi apart \n" ); document.write( ": \n" ); document.write( ": \n" ); document.write( "Check this on a calc; enter |