how do you solve this problem?
4x squared + y squared = 100
I need intercepts and focus?

4x^2 + y^2=100

To find the intercepts, you only need to do what you would in any other intercept situation. (Note that if you were attempting to draw this equation, you would need to put it into the form x^2/a^2 + y^2/b^2 = 1, where a and b are your major and minor axis (The longer radii is your major axis!).

Set one variable equal to zero, and solve for the unknown.

y=0

4x^2=100
x^2=25
x = squareroot(25)

I left x as squareroot(25) because I don't know how to use the reply board to display plus or minus.

You can do the same with y by setting x = 0

your major and minor axis are needed to find the focus where

c^2=b^2-a^2 (You may see this as a^2-b^2 if your major axis lies on the x coordinate!)

where c is the distance from the focus to the vertex (center of your elipse) and a and b are the radii of your major and minor axis

a = 5
b = 10 (These are calculated by finding a and b and expressing the equation in its general form above)

our focus is going to be

c^2 = 10^2 - 5^2
c^2 = 75
c = squareroot(75)

your focus is then 5*squareroot(3)

Hi Nhatkiem, you could look at the sticky thread in this section itself, posted by RickJ. You'll see a LaTeX link to a tutorial so that you can make use of the forum facilities better :) plus minus sign has the \pm code. Using the 'math' tags in square brackets and closing with [/math], you get,

I know I'll get around to using that, but sadly, I'm a very lazy person hahaha, though it would make things a lot neater. Thanks again unknown008.