# Determining restrictions on an ellipse

1. Mar 14, 2005

### trigger352

The equation $$Ax^2 + By^2 + Cx = 1$$ represents an ellipse. If $$A > 0$$ and $$B > 0$$, what conditions must be satisfied if the ellipse has it's major axis on the y-axis?

The answer is "$$C = 0$$ and $$A > B$$"

When I first wrote this question I thought $$A > B$$ should have been $$A < B$$. So how do I figure out what the restrictions are? Why is $$A < B$$ wrong?

Last edited: Mar 14, 2005
2. Mar 14, 2005

### Jameson

Plot an ellipse where A > B and see if the answer is correct... then test your way of A < B.

Jameson

BTW: Your answer is correct. If B > A , then the major axis will run along the y-axis.

Last edited: Mar 14, 2005
3. Mar 14, 2005

### dextercioby

C different from zero would automatically shift the center of the ellipse from the center of coordinates...

Daniel.