SOLUTION: Give the coordinates of the center, foci, and covertices of the ellipse with equation 41x^2 + 16y^2 + 246x - 192y + 289 = 0.

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Question 1044336: Give the coordinates of the center, foci, and covertices of the ellipse with equation 41x^2 + 16y^2 + 246x - 192y + 289 = 0.
Answer by Edwin McCravy(20059) About Me  (Show Source):
You can put this solution on YOUR website!
Give the coordinates of the center, foci, and covertices
of the ellipse with equation
41x^2 + 16y^2 + 246x - 192y + 289 = 0.


Rearrange

41x%5E2%2B246x%2B16y%5E2-192y=-289

Factor out coefficients of squared letters:

41%28x%5E2%2B6x%29%2B16%28y%5E2-12y%29=-289

To complete the squares, we need to add a number to the 
end of each parentheses, and to the right side:

41%28x%5E2%2B6x%2B%22___%22%29%2B16%28y%5E2-12y%2B%22___%22%29%22%22=%22%22-289%2B%22___%22%2B%22___%22
so we put a blank where we need to add numbers.

To complete the square in the first parentheses:

1.  Multiply the coefficient of x by 1%2F2:

       6%2A%281%2F2%29=3

2.  Square that result:

       3%5E2=9

3.  Put that where the first blank is on the left side:

41%28x%5E2%2B6x%2B9%29%2B16%28y%5E2-12y%2B%22___%22%29%22%22=%22%22-289%2B%22___%22%2B%22___%22

So we complete the square in the first parentheses by
adding +9 inside the first parentheses
which actually amounts to adding 41*9 or 369 to the left 
side because there is a 41 in front of the parentheses, so
we must add 369 to the right side:

41%28x%5E2%2B6x%2B9%29%2B16%28y%5E2-12y%2B%22___%22%29%22%22=%22%22-289%2B369%2B%22___%22

To complete the square in the second parentheses:

1.  Multiply the coefficient of y by 1%2F2:

       -12%2A%281%2F2%29=-6

2.  Square that result:

       %28-6%29%5E2=36

3.  Put that 36 in the remaining blank on the left side:

41%28x%5E2%2B6x%2B9%29%2B16%28y%5E2-12y%2B36%29%22%22=%22%22-289%2B369%2B%22___%22

Since we complete the square in the second parentheses by adding +36 
inside the second parentheses, that actually amounts to adding 16*36 
or 576 to the left side because there is a 16 in front of the 
parentheses, so we must add 576 to the right side, so we put 576
in the remaining blank on the right side:

41%28x%5E2%2B6x%2B9%29%2B16%28y%5E2-12y%2B36%29%22%22=%22%22-289%2B369%2B576

We factor both parentheses as perfect squares of binomials,
and combine the numbers on the right side:

41%28x%2B3%29%5E2%2B16%28y-6%29=656

Get a 1 on the right by dividing through by 656

%2841%28x%2B3%29%5E2%29%2F656%2B%2816%28y-6%29%5E2%29%2F656=656%2F656

Simplify. 41 goes into 656 16 times, and 16 goes
into 656 41 times 

%28x%2B3%29%5E2%2F16%2B%28y-6%29%5E2%2F41=1

Since the largest denominator is under the term in
y, the ellipse has a vertical major axis.  So we
compare it to:

%28x-h%29%5E2%2Fb%5E2%2B%28y-k%29%5E2%2Fa%5E2=1

h=-3, k=6, 

b%5E2=9 so b=sqrt%289%29=3

a%5E2=41 so 
 
Draw the major axis a=sqrt%2841%29=6.4 units both above and below the center.
Draw the minor axis b=3 units both right and left of the center.
 


The vertices are a=sqrt%2841%29 units above and below the center (-3,6)

So we add sqrt%2841%29 to the y-coordinate of the center.  So the 
upper vertex is %28matrix%281%2C3%2C-3%2C%22%2C%22%2C6%2Bsqrt%2841%29%29%29

And we subtract sqrt%2841%29 from the y-coordinate of the center.  So the 
upper vertex is %28matrix%281%2C3%2C-3%2C%22%2C%22%2C6-sqrt%2841%29%29%29

The covertices are b=3 units left and right of the center (-3,6)

So we add 3 to the x-coordinate of the center.  So the 
right covertex is (0,6)

And we subtract 3 from the x-coordinate of the center.  So the 
left covertex is (-6,6)

Sketch in the ellipse:
 


To find the foci, we must calculate c, using the Pythagorean
relationship 

c%5E2=a%5E2-b%5E2

c%5E2=%28sqrt%2841%29%29%5E2-3%5E2

c%5E2=41-9

c%5E2=32

c=sqrt%2832%29

c=sqrt%2816%2A2%29

c=4sqrt%282%29

The foci are c=4sqrt%282%29 units above and below the 
center (-3,6)

So we add c=4sqrt%282%29 to the y-coordinate of the center

So the upper focus is %28matrix%281%2C3%2C-3%2C%22%2C%22%2C6%2B4sqrt%282%29%29%29

And we subtract c=4sqrt%282%29 from the y-coordinate of 
the center.

So the lower focus is %28matrix%281%2C3%2C-3%2C%22%2C%22%2C6-4sqrt%282%29%29%29

They are approximately 

(-3,11.7) and (-3,0.34).

We plot the two foci:


Edwin