In each of the Exercises 7 to 12, find the equation of the parabola that satisfies the given conditions: Vertex (0,0); focus (-2,0)
y² = -8x
Explanation
This question tests understanding of standard parabola equations. When the vertex is at origin (0,0) and focus lies on the x-axis, the parabola has its axis along the x-axis. Since the focus (-2,0) lies on the negative x-axis, the parabola opens to the left, making it of the form y² = -4ax. The distance from vertex to focus gives a = 2.
Solution Steps
Step 1: Given vertex (0,0) and focus (-2,0). Since the focus lies on the x-axis, the axis of the parabola is the x-axis.
Step 2: The focus (-2,0) is on the negative x-axis, so the parabola opens to the left. Hence, the equation is of the form y² = -4ax.
Step 3: The distance from vertex to focus is a = 2.
Step 4: Substituting a = 2 in y² = -4ax, we get y² = -4(2)x = -8x.