Find focus and directrix of parabola y² = -8x:
- Focus (0, -2)
- No focus
- Focus (-2, 0), directrix x = 2 (opens left, a = -2)
- Focus (2, 0), directrix x = -2
Show answer and solution
Correct answer: C. Focus (-2, 0), directrix x = 2 (opens left, a = -2)
y² = -8x → 4a = -8 → a = -2. Vertex (0, 0), opens left. Focus (a, 0) = (-2, 0). Directrix x = -a = 2.