document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=212720>Question 212720</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/0321269470/algebrahomeworkh>Introductory Algebra</A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> Please help!! I have tried to come up with a solution...but I am majorly stuck and frustrated!! If I've made an error, I can't see it. And with what I do have, I have no idea what the next step should be. ~ Thanks! Here's the problem and my attempt:\r<BR>\n" );
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document.write( "Boat Speed.     The current in a stream moves at a speed of 3 mph. A boat travels 45 mi upstream and 45 mi downstream in a total time of 8 hr. What is the speed of the boat in still water?\r<BR>\n" );
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document.write( "t(1) = 45/r-3      t(2) = 45/r+3       t(1) + t(2) = 8, where r is the rate of the boat in still water \r<BR>\n" );
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document.write( "45/(r-3)+ 45/(r+3)=8  The LCD is (r-3)(r+3)\r<BR>\n" );
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document.write( "((r-3) (r+3) (45/(r-3)) + ((r-3) (r+3) (45/(r+3)) = 8 (r-3)(r+3) \r<BR>\n" );
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document.write( "45 (r + 3) + 45 (r - 3) = 8 (r^2 – 9)\r<BR>\n" );
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document.write( "45r + 135 + 45r – 135 = 8r^2 – 72\r<BR>\n" );
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document.write( "90r = 8r^2 – 72<BR>\n" );
document.write( "-90r        -90r\r<BR>\n" );
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document.write( "0 = 8r2 – 90r – 72\r<BR>\n" );
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document.write( "Now What? I know the next step is to factor but I can’t determine a factorization in the form of (x + ?)(x - ?)…the best I can do is…\r<BR>\n" );
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document.write( "0 = 2 (r^2 – 45r – 32)\r<BR>\n" );
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document.write( "And IF this is the correct factoring answer…I have NO CLUE what to do next! PLEASE HELP!!<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #160637 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=160637\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 8r^2 -90r-72 = 0<BR>\n" );
document.write( "2(4r^2-45r-36) = 0<BR>\n" );
document.write( "2(r-12)(4r+3) = 0<BR>\n" );
document.write( "Positive solution:<BR>\n" );
document.write( "r = 12<BR>\n" );
document.write( "=============<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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