To find the key points on the graph of the quadratic function \( y = x^2 - 16x + 48 \), we need to determine the vertex, x-intercepts, and y-intercept. We will follow these steps:
Step 1: Find the Vertex
The vertex of a quadratic function in the form \( y = ax^2 + bx + c \) can be found using the formula:
\[
x = -\frac{b}{2a}
\]
For the quadratic \( y = x^2 - 16x + 48 \):
- \( a = 1 \)
- \( b = -16 \)
Calculating the x-coordinate of the vertex:
\[
x = -\frac{-16}{2 \cdot 1} = \frac{16}{2} = 8
\]
Next, substitute \( x = 8 \) back into the equation to find the y-coordinate of the vertex:
\[
y = (8)^2 - 16(8) + 48
\]
\[
y = 64 - 128 + 48 = -16
\]
So, the vertex is:
\[
\text{vertex} = (8, -16)
\]
Step 2: Find the X-Intercepts
To find the x-intercepts, set \( y = 0 \):
\[
0 = x^2 - 16x + 48
\]
We can solve this quadratic equation using the quadratic formula:
\[
x = \frac{{-b \pm \sqrt{{b^2 - 4ac}}}}{2a}
\]
Where \( a = 1 \), \( b = -16 \), and \( c = 48 \):
Calculating the discriminant:
\[
b^2 - 4ac = (-16)^2 - 4 \cdot 1 \cdot 48 = 256 - 192 = 64
\]
Since the discriminant is positive, there are two real and distinct x-intercepts.
Now plug in the values into the quadratic formula:
\[
x = \frac{{16 \pm \sqrt{64}}}{2 \cdot 1} = \frac{{16 \pm 8}}{2}
\]
Calculating the two possible values for \( x \):
-
For the plus sign:
\[
x = \frac{{16 + 8}}{2} = \frac{24}{2} = 12
\]
-
For the minus sign:
\[
x = \frac{{16 - 8}}{2} = \frac{8}{2} = 4
\]
Thus, the x-intercepts are \( x = 4 \) and \( x = 12 \).
Step 3: Find the Y-Intercept
To find the y-intercept, set \( x = 0 \):
\[
y = (0)^2 - 16(0) + 48 = 48
\]
So, the y-intercept is:
\[
\text{y-intercept} = (0, 48)
\]
Final Answers Summary:
- vertex: \( (8, -16) \)
- smaller x-intercept: \( (4, 0) \)
- larger x-intercept: \( (12, 0) \)
- y-intercept: \( (0, 48) \)
Thus, the answer is:
- vertex: \( (8, -16) \)
- (smaller) x-intercept: \( (4, 0) \)
- (larger) x-intercept: \( (12, 0) \)
- y-intercept: \( (0, 48) \)