Answer: x2/9 + y2/25 = 1.
- A x2/9 + y2/25 = 1
- B x2/25 + y2/9 = 1
- C x2/9 - y2/25 = 1
- D x2/5 + y2/3 = 1
Correct answer: A. x2/9 + y2/25 = 1
Explanation: Major axis along y-axis: standard form x²/b²+y²/a²=1 with a=5 (semi-major) and b=3 (semi-minor). So denominators: b²=9 under x², a²=25 under y². Equation: x²/9+y²/25=1. Ans: x²/9+y²/25=1.
All four conics form a single family distinguished only by eccentricity: a circle is the most "closed" (e=0), an ellipse is an elongated closed curve, a parabola is the borderline open curve (e=1), and a hyperbola has two separate open branches (e>1).
Concept context
Study circles, parabolas, ellipses, and hyperbolas as curves formed by intersecting a plane with a double cone, with their standard equations and key properties.