Question

Use the zeros of the following quadratic to find the x-value of the vertex.

y = x2 – 4x – 5
A.5
B.2
C.–2
D.–5

Answer 1

The answer is B.) 2

(on e2020)

Answer 2

1. y = x^2 - 4x - 5
= x^2 - 4x + 4 - 4 - 5
= (x^2 - 4x + 4) -4 - 5
y = (x-2)^2 - 9 Here, the vertex is at (2, -9)

2. x = 2 (the vertical line that goes through the vertex)
3. The graph of this function is called a parabola. To graph a parabola, use
its vertex (in this case, (2, -9) ) and y-intercept (y = -5). The y-intercept is the constant in the given equation. Use the fact that the vertical line through the vertex is a line of symmetry. Plot the point corresponding to the y-intercept that lies on the other side of the vertical line x = 2.

4. The graph is translated 2 units to the right and 9 units down.