Question 1118319
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{{{x^2+4y^2 = 16}}}
{{{x^2/16 + y^2/4 = 1}}}
{{{x^2/4^2 + y^2/2^2 = 1}}}
{{{(x-0)^2/4^2 + (y-0)^2/2^2 = 1}}}
{{{(x-h)^2/a^2 + (y-k)^2/b^2 = 1}}}<br>
The "x-0" and "y-0" mean the center of the ellipse is (h,k) = (0,0).<br>
a.  Answer: the center is C(0,0).<br>
 The denominators are the squares of the semi-major and semi-minor axes.  So the semi-major axis is 4 (in the x direction) and the semi-minor axis is 2 (in the y direction).  So the lengths of the major and minor axes are 8 and 4.<br>
b,c.  Answer: major axis 8; minor axis 4.<br>
"c" is the distance from the center of the ellipse to either focus; for an ellipse, c^2 = a^2 + b^2.<br>
d.  Answer: the distance from the center to each focus is {{{sqrt(16+4) = sqrt(20)}}}