What are the key points on the graph of y = x^2 − 16x + 48? Name the vertex, x-intercepts, and y-intercept.

vertex: (___)
(smaller) x-intercepts: (___)
(larger) x-intercept: (___)
y-intercept: (___)

1 answer

To analyze the quadratic function \( y = x^2 - 16x + 48 \), we will determine the vertex, x-intercepts, and y-intercept.

1. Finding the Vertex

The vertex of a quadratic \( y = ax^2 + bx + c \) can be found using the formula:

\[ x = -\frac{b}{2a} \]

For the function \( y = x^2 - 16x + 48 \):

  • \( a = 1 \)
  • \( b = -16 \)

Substituting into the formula:

\[ x = -\frac{-16}{2 \cdot 1} = \frac{16}{2} = 8 \]

To find the y-coordinate of the vertex, substitute \( x = 8 \) back into the equation:

\[ y = 8^2 - 16 \cdot 8 + 48 \] \[ y = 64 - 128 + 48 = -16 \]

Thus, the vertex is at:

\[ \text{vertex: } (8, -16) \]

2. Finding the x-intercepts

To find the x-intercepts, set \( y = 0 \):

\[ 0 = x^2 - 16x + 48 \]

This is a standard form quadratic equation. We can factor it:

\[ 0 = (x - 12)(x - 4) \]

Setting each factor to zero gives:

\[ x - 12 = 0 \quad \Rightarrow \quad x = 12 \] \[ x - 4 = 0 \quad \Rightarrow \quad x = 4 \]

Thus, the x-intercepts are:

\[ \text{smaller } x\text{-intercept: } (4, 0) \] \[ \text{larger } x\text{-intercept: } (12, 0) \]

3. Finding the y-intercept

To find the y-intercept, set \( x = 0 \):

\[ y = 0^2 - 16 \cdot 0 + 48 = 48 \]

Thus, the y-intercept is:

\[ \text{y-intercept: } (0, 48) \]

Summary of Key Points

  • Vertex: \( (8, -16) \)
  • Smaller x-intercept: \( (4, 0) \)
  • Larger x-intercept: \( (12, 0) \)
  • Y-intercept: \( (0, 48) \)