Posted by Anonymous on Monday, December 29, 2008 at 1:33pm.
Which equation describes a hyperbola?
A. 2x^2 + 2x + 2y^2  6y  11 = 0
B. 6x^2 + 2x  12y^2  11y = 11
C. 6y^2 + 2x  11y = 5
D. 4y^2 + 2y  10x^2 + 2x  6 = 0
Thanks!

Math  Reiny, Monday, December 29, 2008 at 1:54pm
You should recognize certain patterns to the conic section equations.
if the signs of the x^2 and y^2 terms are opposite , then you have a hyperbola,
e.g. (your example)
If their signs are the same and their coefficients are also the same, you have a circle.
e.g. 6x^2 + 9x + 6y^2  4y = 123
If the signs are the same, but their coefficients are different, you have and ellipse
e.g. 6x^2 + 9x + 4y^2  4y = 123
if one of the square terms, either the x or the y, are missing, you have a parabola
4x^2 + 8y = 77
if both square terms are missing you have straight line.