document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=120251>Question 120251</A>: <I><SPAN STYLE=\"word-break: break-all;\"> What value of b will make the expression x^2-bx+40 a perfect square? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #88119 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=88119\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> What value of b will make the expression x^2-bx+40 a perfect square?<BR>\n" );
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document.write( "Perfect Square form: (c-d)^2 = c^2-2cd+d^2<BR>\n" );
document.write( "Your Problem:<BR>\n" );
document.write( "d^2 = 40<BR>\n" );
document.write( "d = 2sqrt(10)<BR>\n" );
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document.write( "c^2=x^2<BR>\n" );
document.write( "c=x<BR>\n" );
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document.write( "-2cd=-bx<BR>\n" );
document.write( "Substitute to get:<BR>\n" );
document.write( "bx = 2x(2sqrt(10))<BR>\n" );
document.write( "bx = 4sqrt(10)x<BR>\n" );
document.write( "b = 4sqrt(10)<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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