document.write( "Question 824121: A man cycled a distance of 42km from his village. On his return journey he increased his speed by 2km/hr and took half an hour less. Calculate the average speed on the journey from his village. \n" ); document.write( "
Algebra.Com's Answer #496113 by josmiceli(19441)\"\" \"About 
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Let \"+r+\" = his rate going from the village in km/hr
\n" ); document.write( "Let \"+t+\" = his time in hrs going from the village
\n" ); document.write( "-------------
\n" ); document.write( "Equation going from the village:
\n" ); document.write( "(1) \"+42+=+r%2At+\"
\n" ); document.write( "Equation for return journey:
\n" ); document.write( "(2) \"+42+=+%28+r%2B2+%29%2A%28+t+-+.5+%29+\"
\n" ); document.write( "-------------------------
\n" ); document.write( "(2) \"+42+=+r%2At+%2B+2t+-+.5r+-+1+\"
\n" ); document.write( "(2) \"+43+%2B+.5r+=+r%2At+%2B+2t+\"
\n" ); document.write( "(2) \"+43+%2B+.5r+=+%28+r+%2B+2+%29%2At+\"
\n" ); document.write( "(2) \"+t+=+%28+43+%2B+.5r+%29+%2F+%28+r+%2B+2+%29+\"
\n" ); document.write( "-----------------------------
\n" ); document.write( "(1) \"+42%2Fr+=+t+\"
\n" ); document.write( "By substitution:
\n" ); document.write( "(1) \"+42%2Fr+=+%28+43+%2B+.5r+%29+%2F+%28+r+%2B+2+%29+\"
\n" ); document.write( "Multiply both sides by \"+r%2A%28+r+%2B+2+%29+\"
\n" ); document.write( "(1) \"+42%2A%28+r%2B2+%29+=+%28+43+%2B+.5r+%29%2Ar+\"
\n" ); document.write( "(1) \"+42r+%2B+84+=+43r+%2B+.5r%5E2+\"
\n" ); document.write( "(1) \"+.5r%5E2+%2B+r+-+84+=+0+\"
\n" ); document.write( "(1) \"+r%5E2+%2B+2r+-+168+=+0+\"
\n" ); document.write( "-----------------------
\n" ); document.write( "\"+r+=+%28-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29+\"
\n" ); document.write( "\"+a+=+1+\"
\n" ); document.write( "\"+b+=+2+\"
\n" ); document.write( "\"+c+=+-42+\"
\n" ); document.write( "\"+r+=+%28-2+%2B-+sqrt%28+2%5E2+-+4%2A1%2A%28-168%29+%29%29+%2F+%282%2A1%29+\"
\n" ); document.write( "\"+r+=+%28-2+%2B-+sqrt%28+4+%2B+672+%29%29+%2F+2+\"
\n" ); document.write( "\"+r+=+%28-2+%2B-+sqrt%28+676+%29%29+%2F+2+\"
\n" ); document.write( "\"+r+=+%28-2+%2B+26%29+%2F+2+\"
\n" ); document.write( "\"+r+=++-1+%2B+13%0D%0A%7B%7B%7B+r+=+12+\"
\n" ); document.write( "His average rate traveling from the village was 12 km/hr
\n" ); document.write( "check:
\n" ); document.write( "(1) \"+42+=+r%2At+\"
\n" ); document.write( "(1) \"+t+=+42%2F12+\"
\n" ); document.write( "(1) \"+t+=+3.5+\"
\n" ); document.write( "-----------------
\n" ); document.write( "(2) \"+42+=+%28+r%2B2+%29%2A%28+t+-+.5+%29+\"
\n" ); document.write( "(2) \"+42+=+%28+12+%2B+2+%29%2A%28+3.5+-+.5+%29+\"
\n" ); document.write( "(2) \"+42+=+14%2A3+\"
\n" ); document.write( "(2) \"+42+=+42+\"
\n" ); document.write( "OK\r
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