document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=453994>Question 453994</A>: <I><SPAN STYLE=\"word-break: break-all;\"> which are related functions <BR>\n" );
document.write( "1-{(5,7),(-2,1),(5,0),(-3,6)}<BR>\n" );
document.write( "2-{(-2,-1),(4,5),(4,-2),(3,4)}<BR>\n" );
document.write( "3-{(0,4),(3,6),(-1,2),(4,0)}<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #311833 by </B><A HREF=/tutors/aboutme.mpl?userid=Edwin+McCravy><B>Edwin McCravy(20059)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Edwin+McCravy><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=Edwin+McCravy><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=311833\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Rule:\r<BR>\n" );
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document.write( "1. Look at all the first coordinates\r<BR>\n" );
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document.write( "2. Then ask the question: Are all those different?\r<BR>\n" );
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document.write( "3. If the answer is yes, then this is a function but if <BR>\n" );
document.write( "the answer is no, then it is not a function.\r<BR>\n" );
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document.write( "Let's try it out on\r<BR>\n" );
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document.write( "1-{(5,7),(-2,1),(5,0),(-3,6)}\r<BR>\n" );
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document.write( "1. Look at all the first coordinates 5, -2, 5, -3\r<BR>\n" );
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document.write( "2. Then ask the question: Are all those different?\r<BR>\n" );
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document.write( "3. The answer is no because there are two 5's, \r<BR>\n" );
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document.write( "So it is NOT a function.\r<BR>\n" );
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document.write( "Now let's try it out on\r<BR>\n" );
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document.write( "2-{(-2,-1),(4,5),(4,-2),(3,4)}\r<BR>\n" );
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document.write( "1. Look at all the first coordinates -2, 4, 4, 3\r<BR>\n" );
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document.write( "2. Then ask the question: Are all those different?\r<BR>\n" );
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document.write( "3. The answer is no because there are two 4's, \r<BR>\n" );
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document.write( "So it is NOT a function.\r<BR>\n" );
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document.write( "Now let's try it out on\r<BR>\n" );
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document.write( "3-{(0,4),(3,6),(-1,2),(4,0)}\r<BR>\n" );
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document.write( "1. Look at all the first coordinates 0, 3, -1, 4\r<BR>\n" );
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document.write( "2. Then ask the question: Are all those different?\r<BR>\n" );
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document.write( "3. The answer is yes because none of them are the same. \r<BR>\n" );
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document.write( "So it IS a function.\r<BR>\n" );
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document.write( "Easy, huh?  Just look and see if all the first coordinates<BR>\n" );
document.write( "are all different or whether some are the same. If they're<BR>\n" );
document.write( "all different then you have a function. If some are the<BR>\n" );
document.write( "same you don't.  [By the way, it doesn't matter at all about <BR>\n" );
document.write( "the second coordinates.  They can be the same or different. <BR>\n" );
document.write( "We only need to look at the first coordinates.]\r<BR>\n" );
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document.write( "Edwin</pre> </SPAN>\n" );
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