Question

What is the vertex for the function: f(x)=(x+1)(x−3) Show how you found the y-coordinate in the space below:

Answer 1

(1;-4).

Explanation:

1. zeros of the given function are: -1 and 3, then

2. the x-coordinate of the vertex is 0.5*(3-1)=1.

3. the y-coordinate of the vertex can be calculated if to substitute x=1 into the given equation:

y=(1+1)(1-3)=-4.

PS. this way is not the only one.