document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=120151>Question 120151</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A quadratic equation has roots 1+-2i.What is the equation? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #88049 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=88049\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A quadratic equation has roots 1+-2i.What is the equation?<BR>\n" );
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document.write( "Sort of like completing the square in reverse:<BR>\n" );
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document.write( "x = 1 +/- 2i<BR>\n" );
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document.write( "x - 1 = +/- 2i; subtract 1 from both sides<BR>\n" );
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document.write( "(x-1)^2 = (+/-2i)^2; square both sides<BR>\n" );
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document.write( "x^2 - 2x + 1 = 4(i^2); FOIL the left side<BR>\n" );
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document.write( "x^2 - 2x + 1 = 4(-1); i^2 = -1<BR>\n" );
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document.write( "x^2 - 2x + 1 = -4<BR>\n" );
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document.write( "x^2 - 2x + 1 + 4 = 0; add 4 to both sides<BR>\n" );
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document.write( "x^2 - 2x + 5 = 0; is the quadratic equation<BR>\n" );
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document.write( "You can check this by completing the square, and see if you get the given roots </SPAN>\n" );
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