(x-3)^2/9 + (y+1)^2/4. the center is (3,-1).....so why is the foci not (3,-1+sqrt5),(3,-1-sqrt5)? my answer for foci is wrong and i don't know why.

Question

anonymous · Answer

i think your orientation is wrong

anonymous · Answer

|dw:1350512834498:dw|

anonymous · Answer

so instead of what you had, it is $\sqrt{5}$ units left and right, not up and down

anonymous · Answer

hope that is clear, and you know it because $9>4$

anonymous · Answer

ie (3,-1+sqrt5)   should be (-1, 3-sqrt5)

anonymous · Answer

i hate to disagree with the great estudier, but i am afraid since it is to the left and right, it should be 
$$(3-\sqrt{5},-1), (3+\sqrt{5},-1)$$

anonymous · Answer

Oops:-)  (I did give u the medal)

anonymous · Answer

merci (that is how i knew to look!)

anonymous · Answer

thank you both!!