document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=622018>Question 622018</A>: <I><SPAN STYLE=\"word-break: break-all;\"> please help me solve for all:\r<BR>\n" );
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document.write( "2cos^2x-cosx=1 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #391109 by </B><A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><B>jim_thompson5910(35256)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><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=391109\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 2cos^2x-cosx=1\r<BR>\n" );
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document.write( "2cos^2x-cosx=1\r<BR>\n" );
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document.write( "2cos^2x-cosx-1=0\r<BR>\n" );
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document.write( "2z^2-z-1=0  .... Let z = cosx\r<BR>\n" );
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document.write( "2z^2-2z+z-1=0\r<BR>\n" );
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document.write( "(2z^2-2z)+(z-1)=0\r<BR>\n" );
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document.write( "2z(z-1)+(z-1)=0\r<BR>\n" );
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document.write( "2z(z-1)+1(z-1)=0\r<BR>\n" );
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document.write( "(2z+1)(z-1)=0\r<BR>\n" );
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document.write( "(2z+1)(z-1)=0\r<BR>\n" );
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document.write( "2z+1=0 or z-1=0\r<BR>\n" );
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document.write( "z=-1/2 or z=1\r<BR>\n" );
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document.write( "cosx=-1/2 or cosx=1\r<BR>\n" );
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document.write( "x=arccos(-1/2) or x=arccos(1)\r<BR>\n" );
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document.write( "x=arccos(-1/2)\r<BR>\n" );
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document.write( "x=2pi/3+2pi*n or x = 4pi/3 + 2pi*n\r<BR>\n" );
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document.write( "x=arccos(1)\r<BR>\n" );
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document.write( "x=2pi*n\r<BR>\n" );
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document.write( "So the solutions are:\r<BR>\n" );
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document.write( "x=2pi/3+2pi*n, x = 4pi/3 + 2pi*n, or x=2pi*n </SPAN>\n" );
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