document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=751524>Question 751524</A>: <I><SPAN STYLE=\"word-break: break-all;\"> cos 2x + cos x = 0 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #457260 by </B><A HREF=/tutors/aboutme.mpl?userid=Cromlix><B>Cromlix(4381)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Cromlix><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/cgi-bin/show-face.mpl?user=Cromlix><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=457260\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> cos2x + cos x<BR>\n" );
document.write( "replace cos 2x with 2cos^2-1<BR>\n" );
document.write( "2cos^2-1 + cos x = 0<BR>\n" );
document.write( "Rearrange<BR>\n" );
document.write( "2cos^2x + cos x - 1 = 0<BR>\n" );
document.write( "(2cosx - 1)(cosx + 1) = 0<BR>\n" );
document.write( " cosx = 1/2 or -1<BR>\n" );
document.write( " <BR>\n" );
document.write( "x = 60 degs, 300degs  and 180degs\r<BR>\n" );
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document.write( "  = pi/3 rads, 5pi/3 rads and pi </SPAN>\n" );
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