Question 859891
<pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi,
9x^2 + 25y^2 = 225
{{{ x^2/5^2 + y^2/3^3 = 1}}}  C(0,0)  x-axis the major axis
sqrt(25-9) = 4 , foci (-4,0) and (4,0)
{{{drawing(300,300,   -6, 6, -6, 6, grid(1),arc(0,0,10,6), 
circle(-4, 0,0.2),
circle(4, 0,0.2),
graph( 300, 300, -6, 6, -6, 6) )}}}
4x^2 + 9y^2 = 144
{{{x^2/6^2 + y^2/4^2 = 4}}} C(0,0) x-axis the major axis
{{{sqrt(36-16) = sqrt(20) = 2sqrt(5)}}}
foci (-{{{2sqrt(5)}}}, 0) and ({{{2sqrt(5)}}}, 0)
{{{drawing(300,300,   -6, 6, -6, 6, grid(1),arc(0,0,12,8), 
circle(-2sqrt(5), 0,0.2),
circle(2sqrt(5), 0,0.2),
graph( 300, 300, -6, 6, -6, 6) )}}}