Question

Who’s the the y-value of the vertex of the function f(x)=-(x+8)(x-14)

Answer 1

The required y-value is -121.

Explanation:

There are several ways in which we could approach this problem. From the two binomial factors (x + 8) and (x - 14), we know that the two roots are x = -8 and x = 14. The axis of symmetry is the vertical line x = 3. This value is halfway between x = -8 and x = 14.

Substituting x = 3 into f(x)= -(x+8)(x-14) results in f(3) = -(11)(-11) = -121.

The vertex is at (3, -121). The required y-value is -121.