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For the ellipse 25x^2+9y^2-126y+200x= 59,

0 votes

find the standard form. then find the center, vertices, foci, and?

asked Jun 17, 2013 in PRECALCULUS by anonymous Apprentice

2 Answers

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The  given  ellipse equation is 25x2+9y2-126y +200x = 59

25x2+200x +9y2-126y =59

Add  400 and 441 to each side

25x2+200x +400 +9y2-126y +441 = 59+400+441

25 ( x2+8x+16 ) +9 ( y2-14y +49 ) = 900

25 ( x+4)2+9 ( y - 7)2= 900

[ 25 ( x+4 )2/ 900 ] +[ 9 ( y - 7)2/ 900 ]  = 0

( x+4 )2/ 36 +( y - 7)2/ 100  = 1

The ellipse  standard  formula  is   ( x - (-4)2) / 36 + ( y - 7)2/ 100 = 1

Therefore centre ( h,k ) = ( -4, 7 )

The  vertical  major  axis  standard  formula  is ( x-h)2/ b2+( y-k)2/ a2= 0

( x -( -4 ))2/ 100 +( y - 7)2/ 36  = 1

a2= 100   =>  a = 10

b2 = 36  => b = 6

Therefore  vertices (  k ± a , h ) =  ( 17 , -4 ) , ( -3,-4 )

c = a2- b2

c2 = 64  => c = 8

Therefore  foci  = ( k ± c, h ) = ( 15 , -4 ) , ( -1, -4 ).

answered Jun 17, 2013 by goushi Pupil

The ellipse 25x 2+ 9y 2- 126y  + 200x  = 59

Vertices are : (h , k + a ), (h , k - a ) = (-4, 17), (-4, -3) and

Foci: (h , k + c ), (h, k - c ) =  (-4, 15), (-4, -1).

0 votes

The ellipse equation image

image

image

To change the expressions (x 2+ 8x ) and (y 2 - 14y ) into a perfect square trinomial,

add (half the x coefficient)² and add (half the y coefficient)²to each side of the equation.

image

image

The standard form for an ellipse is in a form = 1, So divide both sides of equation by 900 to set it equal to 1.

image

image

image

Compare the standardform of ellipseimage

a 2 > b 2

If the larger denominator is under the "y " term, then the ellipse is vertical.Center (h, k ).

a  = length of semi-major axis, b  = length of semi-minor axis.

a  = 10, b  = 6

Center ( - 4, 7 )

Vertices: (h , k + a ), (h , k - a )

= ( -4, 7+10 ), ( -4, 7-10 )

Vertices  (- 4, 17 ), (- 4, - 3 )

c  is the distance from the center to each focus.

image

image

Foci: (h , k + c ), (h, k - c )

= (-4, 7+8), (-4, 7-8)

Foci ( - 4, 15 ), ( - 4, - 1 ).

answered Jun 5, 2014 by david Expert
edited Jun 5, 2014 by david

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