document.write( "Question 198908: Hi my name is Liz I need help with this question
\n" ); document.write( "What are the coordinates of the foci of the graph of the equation 4x2+16y2=16? \n" ); document.write( "

Algebra.Com's Answer #149405 by J2R2R(94) $\"\"$ $\"About$

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4x^2 + 16y^2 = 16\r
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\n" ); document.write( "\n" ); document.write( "x^2/4 + y^2/1 = 1\r
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\n" ); document.write( "\n" ); document.write( "x^2/2^2 + y^2/1^2 = 1\r
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\n" ); document.write( "\n" ); document.write( "X^2/a^2 + y^2/b^2 = 1 where a=2 and b=1.\r
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\n" ); document.write( "\n" ); document.write( "b^2 = a^2(1-e^2) for the eccentricity e and the foci +/- ae\r
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\n" ); document.write( "\n" ); document.write( "1 = 4 (1-e^2); Ľ = 1-e^2 giving e = (3^0.5)/2\r
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\n" ); document.write( "\n" ); document.write( "ae = 3^0.5\r
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\n" ); document.write( "\n" ); document.write( "Therefore the foci are (-3^0.5, 0) and (3^0.5, 0) which are approximately (-1.73205, 0) and (1.73205, 0) \n" ); document.write( "

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