Answer:
C: y = -(x +3)² -1
Step-by-step explanation:
You want the vertex-form equation of the parabola with vertex (-3, -1) and opening downward.
Vertex form
For vertex (h, k), the vertex form equation of a parabola is ...
y = a(x -h)² +k
Given that (h, k) = (-3, -1), the equation will have the form ...
y = a(x -(-3))² + (-1)
y = a(x +3)² -1 . . . . . . . . . . matches choice C
The value of 'a' will be negative when the parabola opens downward. Here, its value is -1.
y = -(x +3)² -1
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Additional comment
Once you identify the left-shift of 3 units as resulting in an equation with (x +3)² as a component, you can make the appropriate answer choice without considering anything else. Of course, the fact that the curve opens downward immediately eliminates choices A and B.
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