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April 23, 2014

April 23, 2014

Posted by **Abbey(Please help)** on Monday, May 3, 2010 at 1:49pm.

9x^2 + 4y^2 - 36x + 8y + 31 = 0

My answer was:

center=(2,1)

v=(-2,10)(-2,-10)

f=(-2,11)(-2,-11)

e=11/3

Where did I make a mistake?

- Math -
**Reiny**, Monday, May 3, 2010 at 3:56pm9x^2 + 4y^2 - 36x + 8y + 31 = 0

9(x^2 - 4x + ...) + 4(y^2 + 2y + ...) = -31

9(x^2 - 4x + 4) + 4(y^2 + 2y + 1) = -31+36+4

9(x-2)^2 + 4(y+1)^2 = 9

(x-2)^2 + (y+1)^2 /(9/4) = 1

my centre is (2,-1)

a^2 = 1

b^2 = 9/4) etc

have you found your error?

- Math -
**Anonymous**, Tuesday, August 28, 2012 at 7:07pm9^2-[(4.2x3.4)-9.28

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