Question

Consider the quadratic function:

f(x) = x2 – 8x – 9
Vertex: ( negative b Over 2a, f ( negative b Over 2 a))
What is the vertex of the function? ( , )

Answer 1

(4, -25)

Explanation:

The function is put into this form: f(x)= Ax^2 + Bx + C

In the equation x^2 - 8x - 9, A is 1, B is -8 and C is -9

The negatives cancel for negative B so 8 is positive.

8/ 2(1) = 4

Now we plug 4 into the function as x to find the y value

4^2 - 8(4) - 9

-25