Question 580470
find the length of the major axis containing the foci of the ellipse whose equation is 10x^2 + 20y^2 = 200 in simplest radical form.
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Standard form of an equation for and ellipse with horizontal major axis: 
(x-h)^2/a^2+(y-k)^2/b^2=1, a>b, (h,k) being the (x,y) coordinates of the center.
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10x^2 + 20y^2 = 200 
divide by 200
x^2/20+y^2/10=1
center: (0,0)
a^2=20
a=√20
length of horizontal major axis=2a=2√20