College

Consider the equation [tex]f(x) = -4x^2 + 24x - 112[/tex].

Find its vertex, determine whether the minimum or maximum value of [tex]f[/tex] occurs at the vertex, and find this minimum or maximum value.

A. Vertex: (3, -76); Maximum value: -76

B. Vertex: (3, -76); Minimum value: -76

C. Vertex: (-3, -220); Minimum value: -220

D. Vertex: (-3, -220)

Answer :

To solve the problem of finding the vertex and determining whether the function has a maximum or minimum value, we start by analyzing the quadratic function given:

[tex]\[ f(x) = -4x^2 + 24x - 112 \][/tex]

### Step 1: Find the Vertex

The vertex of a quadratic function in the form [tex]\( f(x) = ax^2 + bx + c \)[/tex] can be found using the formula for the x-coordinate of the vertex:

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

For our function, [tex]\( a = -4 \)[/tex], [tex]\( b = 24 \)[/tex], and [tex]\( c = -112 \)[/tex].

#### Calculate the x-coordinate of the vertex:

[tex]\[ x = -\frac{24}{2(-4)} = -\frac{24}{-8} = 3 \][/tex]

#### Calculate the y-coordinate of the vertex:

We substitute [tex]\( x = 3 \)[/tex] back into the function to find the y-coordinate:

[tex]\[ f(3) = -4(3)^2 + 24(3) - 112 \][/tex]
[tex]\[ f(3) = -4(9) + 72 - 112 \][/tex]
[tex]\[ f(3) = -36 + 72 - 112 \][/tex]
[tex]\[ f(3) = 36 - 112 \][/tex]
[tex]\[ f(3) = -76 \][/tex]

So, the vertex of the function is [tex]\( (3, -76) \)[/tex].

### Step 2: Determine Maximum or Minimum Value

The function [tex]\( f(x) = ax^2 + bx + c \)[/tex] takes a maximum value if [tex]\( a < 0 \)[/tex] and a minimum value if [tex]\( a > 0 \)[/tex].

Since [tex]\( a = -4 \)[/tex] in our case, which is less than 0, the function has a maximum value.

### Conclusion

The vertex of the function is [tex]\( (3, -76) \)[/tex], and since the parabola opens downwards, the maximum value of the function is [tex]\(-76\)[/tex].

Thus, the answer is:
- Vertex: [tex]\( (3, -76) \)[/tex]
- Maximum value: [tex]\(-76\)[/tex]