What is the equation of the parabola with a vertex at (-2, 3) and a focus at (-2, 0)? Does it open upward or downward?a.(x + 2)883-12-01-00-00_files/i0060000.jpg = 0.4(y - 3); upwardc.(x + 2)883-12-01-00-00_files/i0060001.jpg = -12(y - 3); downwardb.(x + 2)883-12-01-00-00_files/i0060002.jpg = 8(y - 3); upwardd.(x + 2)883-12-01-00-00_files/i0060003.jpg = -8(y - 3); downward
Accepted Solution
A:
Refer to the diagram shown below.
The distance, d, from the focus to a point P (x,y) is equal to the distance from the directrix to P. Therefore d² = (6 - y)² = (x + 2)² + y² That is, 36 - 12y + y² = (x + 2)² + y² 12y = -(x + 2)² + 36
The equation of the parabola is y = -(1/12)(x + 2)² + 3 It may be written as -12(y - 3) = (x + 2)²
The leading coefficient -1/12 is negative, therefore the curve opens downward.
Answer: The equation is (x + 2)² = -12(y - 3). The curve opens downward.