document.write( "Question 656751: How do you determine if y is a function of x in: y^2=7x \n" ); document.write( "
Algebra.Com's Answer #409624 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "y² = 7x\r\n" );
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document.write( "It is not a function because, for instance,\r\n" );
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document.write( "(7,7) and (7,-7) are both solutions, since:\r\n" );
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document.write( "(7)² = 7(7)\r\n" );
document.write( "  49 = 49\r\n" );
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document.write( "But also\r\n" );
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document.write( "(-7)² = 7(7)\r\n" );
document.write( "   49 = 49\r\n" );
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document.write( "In a function the same value of x cannot correspond \r\n" );
document.write( "to two different values of y.\r\n" );
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document.write( "However, (7,7) and (7,-7) have the same x-values \r\n" );
document.write( "but different y-values.\r\n" );
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document.write( "Also the graph of y² = 7x is this:\r\n" );
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document.write( "And it does not pass the vertical line test, because\r\n" );
document.write( "these vertical lines (in green) intersect the graph\r\n" );
document.write( "in two places, which a function cannot have.\r\n" );
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document.write( "Edwin
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