document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=596100>Question 596100</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Here's an equation:\r<BR>\n" );
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document.write( "x=sqrt(15-2x)\r<BR>\n" );
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document.write( "This is how I solved it:\r<BR>\n" );
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document.write( "x^2=15-2x<BR>\n" );
document.write( "x^2+2x-15=0<BR>\n" );
document.write( "(x+5)*(x-3)=0<BR>\n" );
document.write( "therefore x=-5 or x=3 and after checking I found that both solutions satisfies the original equation [because 3=sqrt(9) and -5=sqrt(25)]<BR>\n" );
document.write( "But after checking the answers, I found that -5 is considered as an extraneous root as -5 is not equal to sqrt(25), namely 5. But the square root of 25 can be both 5 or -5. \r<BR>\n" );
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document.write( "Can anyone tell me why? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #377513 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=377513\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Actually, the square root of 25 is only 5 because the square root function is what it says it is: a function.\r<BR>\n" );
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document.write( "A function takes one input and spits out only ONE output. So it can't take in the input 25 and spit out both 5 and -5 at the same time.\r<BR>\n" );
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document.write( "So <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sqrt%2825%29=5 ALIGN=MIDDLE  ALT=\"sqrt%2825%29=5\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "When we want the plus/minus to be in there, we have to explicitly add it like so <IMG STYLE=\"max-width:80%;\" src=\"http://latex.codecogs.com/png.latex?\LARGE \pm\sqrt{25}=\pm 5\" title=\"x\" /> </SPAN>\n" );
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