document.write( "Question 1157547: The current of a river is 2 miles per hour. It takes a motorboat a total of 3 hours to travel 8 miles upstream and return 8 miles downstream. What is the speed of the boat in still water? \n" ); document.write( "
Algebra.Com's Answer #780446 by MathTherapy(10552)\"\" \"About 
You can put this solution on YOUR website!

\n" ); document.write( "The current of a river is 2 miles per hour. It takes a motorboat a total of 3 hours to travel 8 miles upstream and return 8 miles downstream. What is the speed of the boat in still water?
\n" ); document.write( "
Let speed of boat in still water be S
\n" );
document.write( "Then we get the following TIME equation: \"matrix%281%2C3%2C+3%2C+%22=%22%2C+8%2F%28S+-+2%29+%2B+8%2F%28S+%2B+2%29%29\"
\n" );
document.write( "3(S - 2)(S + 2) = 8(S + 2) + 8(S - 2) ------- Multiplying by LCD, (S - 2)(S + 2) 
\n" );
document.write( "\"matrix%281%2C3%2C+3%28S%5E2+-+4%29%2C+%22=%22%2C+8S+%2B+16+%2B+8S+-+16%29\"
\n" );
document.write( "\"matrix%281%2C3%2C+3S%5E2+-+12%2C+%22=%22%2C+16S%29\"
\n" );
document.write( "\"matrix%281%2C3%2C+3S%5E2+-+16S+-+12%2C+%22=%22%2C+0%29\"
\n" );
document.write( "\"matrix%281%2C3%2C+3S%5E2+-+18S+%2B+2S+-+12%2C+%22=%22%2C+0%29\"
\n" );
document.write( "3S(S - 6) + 2(S - 6) = 0____(S - 6)(3S + 2) = 0
\n" );
document.write( "Speed in still water, or \"highlight_green%28matrix%281%2C4%2C+S%2C+%22=%22%2C+6%2C+mph%29%29\"               OR               \"matrix%281%2C4%2C+S%2C+%22=%22%2C+-+2%2F3%2C+mph%29\"(ignore) 
\n" );
document.write( "As you probably noticed, you DON'T need to use the quadratic equation as the other person did!! It's TOTALLY UNNECESSARY, unless you have no other means of factoring the trinomial. 
\n" );
document.write( "If you don't, I believe that you need to learn it! \n" );
document.write( "
\n" );