document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=343420>Question 343420</A>: <I><SPAN STYLE=\"word-break: break-all;\"> (Modeling) Airplane Landing Speed\r<BR>\n" );
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document.write( "To determine the appropriate landing speed of a small airplane, the formula<BR>\n" );
document.write( "D= .1s^2 - 3s + 22\r<BR>\n" );
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document.write( "is used, where s is the intitial landing speed in feet per second and D is the length of the runway in feet.  If the landing speed is too fast, the pilot may run out of runway; if the speed is too slow, the plane may stall.  If the runway is 800 ft long, what is the appropriate landing speed? Round to the nearest tenth. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #245742 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=245742\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Airplane Landing Speed <BR>\n" );
document.write( "To determine the appropriate landing speed of a small airplane, the formula<BR>\n" );
document.write( "D= .1s^2 - 3s + 22 <BR>\n" );
document.write( "is used, where s is the intitial landing speed in feet per second and D is the length of the runway in feet. If the landing speed is too fast, the pilot may run out of runway; if the speed is too slow, the plane may stall. If the runway is 800 ft long, what is the appropriate landing speed? Round to the nearest tenth.<BR>\n" );
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document.write( "Solve::: <BR>\n" );
document.write( "0.1s^2 - 3s + 22 = 800<BR>\n" );
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document.write( "Rearrange:<BR>\n" );
document.write( "0.1s^2 - 3s - 778 = 0<BR>\n" );
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document.write( "Quadratic Formula:<BR>\n" );
document.write( "s = [3 +- sqrt(9 - 4*0.1*-778)]/(0.2)<BR>\n" );
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document.write( "s = [3 +- sqrt(9 + 320.2)]/0.2<BR>\n" );
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document.write( "Positive Solution:<BR>\n" );
document.write( "s = [21.14]/0.2<BR>\n" );
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document.write( "s = 105.71 mph<BR>\n" );
document.write( "====================<BR>\n" );
document.write( "Note: My calculator says the answer is 104.47 mph<BR>\n" );
document.write( "Check it out.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.   </SPAN>\n" );
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