Answer:
Option B: [tex]y = -\frac{1}{2} x^2[/tex]
Step-by-step explanation:
The parabola has its concavity downwards, so we need a function in the model:
[tex]y = ax^2 + bx + c[/tex]
With a negative value of 'a'
The vertex is (0,0), so we have that:
[tex]0 = 0a + 0b + c[/tex]
[tex]c = 0[/tex]
The x-coordinate of the vertex is given by the equation:
[tex]x\_vertex = -b/2a[/tex]
[tex]-b/2a = 0[/tex]
[tex]b = 0[/tex]
So we have a function in the model:
[tex]y = ax^2[/tex]
With a < 0
The only option with this format is B:
[tex]y = -\frac{1}{2} x^2[/tex]
