Question

-=[Medal]=-

What are the foci of the graph x2 – 4y2 = 16?

(+/- 4.5, 0)
(+/- 3.9, 0)
(+/- 4.1, 0)
(+/- 2.2, 0)

Answer 1

@iGreen

Answer 2

its either a or c? what did you get

Answer 3

i think its c

Answer 4

not too sure

Answer 5

The equation of a hyperbola is
$$
{x^2\over a^2}-{y^2\over b^2}=1
$$

In your equation a=4 and b = 2
Also, the distance \(c\) from the center to either focus is
$$
c^2=a^2+b^2
$$



Just plug in a and b to get c, the x-coordinate of your focus. Since this is an east-west parabola symmetric about the x-axis, the y-coordinate is zero.

see - http://en.wikipedia.org/wiki/Hyperbola
http://www.wolframalpha.com/input/?i=x%5E2-4y%5E2+%3D+16