document.write( "Question 1149799: the speed of a boat in still water is 15 km/hr. it needs four
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Algebra.Com's Answer #771142 by ikleyn(52781) $\"\"$ $\"About$

You can put this solution on YOUR website!
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document.write( "The time equation is\r\n" );
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document.write( "     -  = 4   hours.\r\n" );
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document.write( "It is literal translation English to Math.\r\n" );
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document.write( "    63*(15+x) - 63*(15-x) = 4*(15^2-x^2)\r\n" );
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document.write( "Reduce this quadratic equation to the standard form and solve it by any method you know.\r\n" );
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document.write( "Here x is the speed of the current.\r\n" );
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document.write( "    //  Without any complicated calculations, I see the answer by my non-armed eye: x= 6 miles per hour for the rate of the current.\r\n" );
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document.write( "        You may confirm it by solving quadratic equation formally.\r\n" );
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\n" ); document.write( "\n" ); document.write( "To see many other similar solved problems, see the lessons\r
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\n" ); document.write( "\n" ); document.write( "    - Unpowered raft floating downstream along a river\r
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\n" ); document.write( "\n" ); document.write( "Also, you have this free of charge online textbook in ALGEBRA-I in this site\r
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\n" ); document.write( "\n" ); document.write( "The referred lessons are the part of this textbook under the section \"Word problems\", the topic \"Travel and Distance problems\".\r
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\n" ); document.write( "\n" ); document.write( "Save the link to this online textbook together with its description\r
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\n" ); document.write( "\n" ); document.write( "Free of charge online textbook in ALGEBRA-I
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