document.write( "Question 275955: Carl and Kyle leave Kyle's house at the same time. Carl drives north and Kyle drives West. Carl's average speed is 9 mph slower than Kyle's. At the end of one hour, they are 45 miles apart. Find the average speed of Kyle. (Round off your answer to the nearest tenth). \n" ); document.write( "
Algebra.Com's Answer #201259 by ankor@dixie-net.com(22740)\"\" \"About 
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Carl and Kyle leave Kyle's house at the same time.
\n" ); document.write( " Carl drives north and Kyle drives West.
\n" ); document.write( " Carl's average speed is 9 mph slower than Kyle's.
\n" ); document.write( " At the end of one hour, they are 45 miles apart.
\n" ); document.write( " Find the average speed of Kyle. (Round off your answer to the nearest tenth).
\n" ); document.write( ":
\n" ); document.write( "Let s = K's driving speed
\n" ); document.write( "then
\n" ); document.write( "(s-9) = C's driving speed
\n" ); document.write( ":
\n" ); document.write( "Solve this as a right triangle: a^2 + b^2 = c^2
\n" ); document.write( "where the distance after 1 hr is:
\n" ); document.write( "a = 1s
\n" ); document.write( "b = 1(s-9)
\n" ); document.write( "c = 45
\n" ); document.write( ":
\n" ); document.write( "s^2 + (s-9)^2 = 45^2
\n" ); document.write( "A quadratic equation
\n" ); document.write( "s^2 + s^2 - 18s + 81 = 2025
\n" ); document.write( ":
\n" ); document.write( "2s^2 - 18s + 81 - 2025 = 0
\n" ); document.write( ":
\n" ); document.write( "2s^2 - 18s - 1944 = 0
\n" ); document.write( "Simplify, divide by 2
\n" ); document.write( "s^2 - 9s - 972 = 0
\n" ); document.write( "Fortunately this will factor
\n" ); document.write( "(s - 36)(s + 27) = 0
\n" ); document.write( "Positive solution
\n" ); document.write( "s = 36 mph is K's speed
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check solution using a calc:
\n" ); document.write( "Enter: \"sqrt%2836%5E2+%2B+27%5E2%29\" = 45; confirms our solution \n" ); document.write( "
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