Question

What is the equation of the ellipse with foci at (5, 0), (-5, 0) and vertices (9, 0), (-9, 0)?
Answers:
x2/81+y2/25=1
x2/81-y2/25=1
x2/81+y2/56=1
x2/81-y2/56=1

Answer 1

@yrelhan4

Answer 2

coordinates of focii are (+/-ae,0).. and coordinates of vertices are.. (=/-a,0).. and e=sqrt(1-[(b/a)]^2).. using the first two. find the value of e.. once you have e.. using the third relation find the value of b.. once you have a and b.. you can easily check which equation satisfies..

Answer 3

where 2a=length of major axis.. 2b=length of minor axis.. e=eccentricity.
i hope you know these terms..

Answer 4

yea I do My answer that I got is A

Answer 5

hmm. give me a minute.

Answer 6

i am not able to solve it for some reason.. lets solve together and tell me where i'm going wrong..

Answer 7

so.. ae=5 and a=9.. right?

Answer 8

yea

Answer 9

e=5/9=sqrt(1-(b^2/a^2))..

Answer 10

--> b^2/a^2=1-25/81..

Answer 11

=56/25 --> b^2=56..

Answer 12

oh wait.. oh i did that wrong..

Answer 13

b^2/a^2=56/81 -->b^2=56..

Answer 14

so your answer should be C..

Answer 15

I see where I made my mistake Thank You

Answer 16

Cheers.