document.write( "Question 421565: Choose the equation that best represents an ellipse for the given foci and co-vertices.\r
\n" ); document.write( "\n" ); document.write( "foci (+or- 2, 0)
\n" ); document.write( "co-vertices (0, +or- 4)\r
\n" ); document.write( "\n" ); document.write( "(a) x^2/20 + y^2/16 =1
\n" ); document.write( "(b) x^2/16 + y^2/20 =1
\n" ); document.write( "(c) x^2/9 - y^2/36= 1
\n" ); document.write( "(d) y^2/6 - x^2/1 =1 \n" ); document.write( "

Algebra.Com's Answer #294398 by Edwin McCravy(20060) $\"\"$ $\"About$

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Choose the equation that best represents an ellipse for the given foci and co-vertices.
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document.write( "foci (+or- 2, 0)\r\n" );
document.write( "co-vertices (0, +or- 4)\r\n" );
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document.write( "(a) x^2/20 + y^2/16 =1\r\n" );
document.write( "(b) x^2/16 + y^2/20 =1\r\n" );
document.write( "(c) x^2/9 - y^2/36= 1\r\n" );
document.write( "(d) y^2/6 - x^2/1 =1\r\n" );
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document.write( "All the choices have center (0,0)\r\n" );
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document.write( "It can't be (c) or (d) for the minus sign tells us they're\r\n" );
document.write( "hyperbolas, not ellipses.\r\n" );
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document.write( "It can't be (b) because the smaller denominator being \r\n" );
document.write( "under the x² term means the ellipse has vertices and foci \r\n" );
document.write( "on the y-axis and covertices on the x-axis, and is shaped \r\n" );
document.write( "like this \"\" . But the given foci are on the x-axis and \r\n" );
document.write( "the covertices are on the y-axis, making it shaped like \r\n" );
document.write( "this \"\". So by elimination, the answer is (a).\r\n" );
document.write( "Edwin

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