Question

Which function has a vertex at (2, –9)?

Answer 1

The function with a vertex at (2, –9) is 1/20 (x - 2)² - 9

Given:

The vertex is the point (2, -9)

Step-by-step explanation:

The completed square format of a quadratic is given as:

y = a (x + b/2a)² + k

Where, b/2a = 2; k = -9

On substituting the values, we get,

y = a(x - 2)² - 9

The x vertex is:

x = (-1) × (-2) = 2

The y vertex is:

y = -9

On substituting the point,  we get,

-4 = a(12 - 2)² - 9

-4 = a(100) - 9

a = 5/100 = 1/20

Now,

∴ y = 1/20 (x - 2)² - 9

Answer 2

Answer:It’s the third one

Step-by-step explanation:

I just completed it