document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=177500>Question 177500</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Solve for x in log form\r<BR>\n" );
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document.write( "4^2X-4^X-42=0\r<BR>\n" );
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document.write( "answer: log(base 4)7 = X </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #132530 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=132530\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Solve for x in log form <BR>\n" );
document.write( "4^2X-4^X-42=0 <BR>\n" );
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document.write( "Let 4^x = w<BR>\n" );
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document.write( "Substitute to get:<BR>\n" );
document.write( "w^2 - w - 42 = 0<BR>\n" );
document.write( "(w-7)(w+6) = 0<BR>\n" );
document.write( "w = 7 or w = -6<BR>\n" );
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document.write( "Substitute to solve for \"x\":<BR>\n" );
document.write( "4^x = 7 or 4^x = -6<BR>\n" );
document.write( "No power of 4 can equal -6 so the only solution is that of 4^x=7<BR>\n" );
document.write( "Takethe log of both sides to get:<BR>\n" );
document.write( "xlog(4) = log(7)<BR>\n" );
document.write( "x = log(7)/log(4)<BR>\n" );
document.write( "x = 1.4036775...<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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