Engineering Board Exam Reviewer · Parabolas · medium

Find the focus of the parabola y2-6y-8x+1=0.

1. (-1,3)
2. (1,3)
3. (3,1)
4. (1,-3)

Answer

B. (1,3)

Solution

Complete the square: (y-3)2=8x+8=8(x+1). The vertex is (-1,3) and p=2, so the focus is (1,3).

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