document.write( "Question 540656: 74.) Sketch the ellipse. Identify the center, vertices, and foci.\r
\n" ); document.write( "\n" ); document.write( "9(x+4)^2+(y+7)^2=81 \n" ); document.write( "
Algebra.Com's Answer #353880 by lwsshak3(11628)\"\" \"About 
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Sketch the ellipse. Identify the center, vertices, and foci.
\n" ); document.write( "9(x+4)^2+(y+7)^2=81
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\n" ); document.write( "Standard form of equation for an ellipse with vertical major axis:
\n" ); document.write( "(x-h)^2/b^2+(y-k)^2/a^2=1,a>b, with(h,k) being the (x,y) coordinates of the center.
\n" ); document.write( "..
\n" ); document.write( "9(x+4)^2+(y+7)^2=81
\n" ); document.write( "divide by 81
\n" ); document.write( "(x+4)^2/9+(y+7)^2/81=1
\n" ); document.write( "center: (-4,-7)
\n" ); document.write( "a^2=81
\n" ); document.write( "a=9
\n" ); document.write( "vertices: (-4,-7±a)=(-4,-7±9)=(-4,2) and (-4,-16)
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\n" ); document.write( "b^2=9
\n" ); document.write( "b=3
\n" ); document.write( "..
\n" ); document.write( "c^2=a^2-b^2=81-9=72
\n" ); document.write( "c=√72≈8.5
\n" ); document.write( "Foci: (-4,-7±c)=(-4,-7±8.5)=(-4,1.5) and (-4,-15.5)
\n" ); document.write( "..
\n" ); document.write( "see graph below as a visual check:
\n" ); document.write( "y=±(81-9(x+4)^2)^.5-7
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