Create a graph; then answer the following question.

What are the key points on the graph of y=x2−8x ? Name the vertex, x-intercept(s), and y-intercept.

(1 point)
Responses

x-intercept: (4,−16)

y-intercept: (0,0)

vertex: (8,0)

x -intercept: left parenthesis 4 comma negative 16 right parenthesis y -intercept: left parenthesis 0 comma 0 right parenthesis vertex: left parenthesis 8 comma 0 right parenthesis

x-intercepts: (0,0) (8,0)

y-intercept: (0,0)

vertex: (4,−16)

x -intercepts: left parenthesis 0 comma 0 right parenthesis left parenthesis 8 comma 0 right parenthesis y -intercept: left parenthesis 0 comma 0 right parenthesis vertex: left parenthesis 4 comma negative 16 right parenthesis

x-intercept: (0,8)

y-intercept: (0,0)

vertex: (4,−16)

x -intercept: left parenthesis 0 comma 8 right parenthesis y -intercept: left parenthesis 0 comma 0 right parenthesis vertex: left parenthesis 4 comma negative 16 right parenthesis

x-intercepts: (0,0) (0,8)

vertex: (4,−16)

There is no y-intercept.

1 answer

To analyze the quadratic function \( y = x^2 - 8x \), we first need to rewrite it in vertex form by completing the square, or we can simply utilize the formula for the vertex and the intercepts.

1. Finding the Vertex

The standard form of a quadratic equation is given by: \[ y = ax^2 + bx + c \] where \( a = 1 \), \( b = -8 \), and \( c = 0 \).

The x-coordinate of the vertex can be found using: \[ x = -\frac{b}{2a} = -\frac{-8}{2 \cdot 1} = \frac{8}{2} = 4 \]

Substituting \( x = 4 \) back into the equation to get the y-coordinate: \[ y = (4)^2 - 8(4) = 16 - 32 = -16 \] Thus, the vertex is \( (4, -16) \).

2. Finding the x-intercepts

To find the x-intercepts, set \( y = 0 \): \[ 0 = x^2 - 8x \] Factoring gives: \[ 0 = x(x - 8) \] This yields two solutions: \[ x = 0 \quad \text{and} \quad x = 8 \] Therefore, the x-intercepts are \( (0, 0) \) and \( (8, 0) \).

3. Finding the y-intercept

To find the y-intercept, set \( x = 0 \): \[ y = (0)^2 - 8(0) = 0 \] So, the y-intercept is \( (0, 0) \).

Summary

  • Vertex: \( (4, -16) \)
  • x-intercepts: \( (0, 0) \) and \( (8, 0) \)
  • y-intercept: \( (0, 0) \)

Selecting the Correct Response

From the available options, the correct response would be:

  • Vertex: \( (4, -16) \)
  • x-intercepts: \( (0, 0) \) and \( (8, 0) \)
  • y-intercept: \( (0, 0) \)

There's no mention of the alternative combinations listed in your choices; however, the key points are definitively represented here.