document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=770305>Question 770305</A>: <I><SPAN STYLE=\"word-break: break-all;\"> solve for x in the equation: arc tan (x+1)+arc tan (x-1)=arc tan (12) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #469531 by </B><A HREF=/tutors/aboutme.mpl?userid=lwsshak3><B>lwsshak3(11628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=lwsshak3><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=469531\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> solve for x in the equation: arc tan (x+1)+arc tan (x-1)=arc tan (12)<BR>\n" );
document.write( "***<BR>\n" );
document.write( "let angle A=arc tan (x+1)<BR>\n" );
document.write( "let angle B=arc tan (x-1)<BR>\n" );
document.write( "let angle C=arc tan (12)<BR>\n" );
document.write( "A+B=C<BR>\n" );
document.write( "tan(A+B)=tan(C)<BR>\n" );
document.write( "..<BR>\n" );
document.write( "Identity: tan(A+B)=(tanA+tanB)/(1-tanA*tanB)<BR>\n" );
document.write( "(x+1+x-1)/(1-(x+1)(x-1))=2x/1-x^2+1=2x/(2-x^2)<BR>\n" );
document.write( "tan(A+B)=tan(C)<BR>\n" );
document.write( "2x/(2-x^2)=12<BR>\n" );
document.write( "2x=24-12x^2<BR>\n" );
document.write( "12x^2+2x-24=0<BR>\n" );
document.write( "6x^2+x-12=0<BR>\n" );
document.write( "(2x+3)(3x-4)=0<BR>\n" );
document.write( "x=-3/2<BR>\n" );
document.write( "or<BR>\n" );
document.write( "x=4/3<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );