document.write( "Question 687196: Draw a picture of each of the functions below, and explain whether or not each is a function, and how you know. (There are 4 graphs with these 4 functions because you also have to draw these functions but I didn't know how to put the graph here)\r
\n" ); document.write( "\n" ); document.write( "a) \"%28x-2%29%5E2%2By%5E2=4\"
\n" ); document.write( "b) \"x%5E2%2B4x%2By=4\"
\n" ); document.write( "c) \"x%2By=4\"
\n" ); document.write( "d) \"xy=4\"
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Algebra.Com's Answer #425096 by MathLover1(20850)\"\" \"About 
You can put this solution on YOUR website!
a) \"%28x-2%29%5E2%2By%5E2=4\"\r
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\n" ); document.write( "\n" ); document.write( "It's the one that has y^2 in it because you could have one x value with two different y values ( a positive and a negative, since y^2 is positive for both).\r
\n" ); document.write( "\n" ); document.write( "If you you use only \"y+=+sqrt%28-%28x-2%29%5E2%2B4%29\" you wold have a \"semicircle\", which is a \"function\".\r
\n" ); document.write( "\n" ); document.write( "On a graph, the idea of single valued means that no vertical line would ever cross more than one value.\r
\n" ); document.write( "\n" ); document.write( "If it crosses more than once it is still a valid curve, but it would not be a function.\r
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\n" ); document.write( "\n" ); document.write( "b) \"x%5E2%2B4x%2By=4\"\r
\n" ); document.write( "\n" ); document.write( "\"+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+x%5E2%2B4x-4%29+\"\r
\n" ); document.write( "\n" ); document.write( "it is a function\r
\n" ); document.write( "\n" ); document.write( "c) \"x%2By=4\"\r
\n" ); document.write( "\n" ); document.write( "\"+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+-x%2B4%29+\"\r
\n" ); document.write( "\n" ); document.write( "d) \"xy=4\"\r
\n" ); document.write( "\n" ); document.write( "\"+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+4%2Fx%29+\"\r
\n" ); document.write( "\n" ); document.write( "this is hyperbola\r
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\n" ); document.write( "\n" ); document.write( "not all hyperbolas are functions, but the one you have \"IS\" a function It can also be written as:\r
\n" ); document.write( "\n" ); document.write( "\"y+=+4%2Fx+\"\r
\n" ); document.write( "\n" ); document.write( "the ones that are \"NOT\" functions are in the form of \"x%5E2%2Fa%5E2+-+y%5E2%2Fb%5E2+=+1\"; whenever \"y\" is \"squared\", you do \"not\"\"+have\" a \"functions\"\r
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