Chapter 3: Problem 21
Find the vertex of the graph of each quadratic function. $$f(x)=3 x^{2}-12 x+1$$
Short Answer
Expert verified
The vertex is (2, -11).
Step by step solution
01
Identify the coefficients
For the quadratic function in the form of \( f(x) = ax^2 + bx + c \), identify the coefficients. Here, \( a = 3 \), \( b = -12 \), and \( c = 1 \)
02
Use the vertex formula
The x-coordinate of the vertex of a quadratic function is given by the formula \( x = \frac{-b}{2a} \). Substitute the coefficients into the formula. \( x = \frac{-(-12)}{2 \cdot 3} = \frac{12}{6} = 2 \).
03
Find the y-coordinate
Substitute the x-coordinate back into the original function to find the y-coordinate. \( f(2) = 3(2)^2 - 12(2) + 1 = 3 \cdot 4 - 24 + 1 = 12 - 24 + 1 = -11 \).
04
Write the vertex
Combine the x-coordinate and y-coordinate as an ordered pair. The vertex is \( (2, -11) \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Functions
A quadratic function is a type of polynomial function that takes the form: \(f(x) = ax^2 + bx + c\). These functions graph as parabolas, which are U-shaped curves.
Quadratic functions have several key properties, such as:
Quadratic functions have several key properties, such as:
- They can open upwards or downwards depending on the coefficient \(a\).
- The highest or lowest point on the graph is called the vertex.
- They possess a symmetrical axis that goes through the vertex.
Vertex Formula
The vertex formula is crucial for finding the vertex of a quadratic function.
The general form of the vertex formula for the x-coordinate of the vertex is given by: \( x = \frac{-b}{2a}\)
To use this formula, you:
This process allows you to derive the vertex as an ordered pair \((x_v, y_v)\).
The general form of the vertex formula for the x-coordinate of the vertex is given by: \( x = \frac{-b}{2a}\)
To use this formula, you:
- Identify the coefficients \(a\) and \(b\) of the quadratic function.
- Substitute these values into the vertex formula.
This process allows you to derive the vertex as an ordered pair \((x_v, y_v)\).
Coefficients of a Quadratic Function
The coefficients of a quadratic function in the standard form \(f(x) = ax^2 + bx + c\) play significant roles in determining the properties of the graph.
Here,
Key points include:
Here,
- \(a\) is the coefficient of \(x^2\),
- \(b\) is the coefficient of \(x\), and
- \(c\) is the constant term.
Key points include:
- \(a\) determines the direction of the parabola (upward if \(a > 0\), downward if \(a < 0\)).
- \(b\) influences the vertex's position horizontally on the graph.
X-Coordinate and Y-Coordinate
Finding the x-coordinate and y-coordinate of the vertex involves simple steps.
First, use the vertex formula to find the x-coordinate: \(x = \frac{-b}{2a}\).
Next, substitute the x-coordinate back into the quadratic function to find the corresponding y-coordinate, \(f(x)\). For example, for the function \(f(x) = 3x^2 - 12x + 1\):
1. Identify coefficients: \(a = 3\), \(b = -12\).
2. Apply vertex formula: \(x = \frac{-(-12)}{2*3} = 2\).
3. Find y-coordinate: \(f(2) = 3(2^2) - 12(2) + 1 = -11\).
So, the vertex is at \((2, -11)\).
First, use the vertex formula to find the x-coordinate: \(x = \frac{-b}{2a}\).
Next, substitute the x-coordinate back into the quadratic function to find the corresponding y-coordinate, \(f(x)\). For example, for the function \(f(x) = 3x^2 - 12x + 1\):
1. Identify coefficients: \(a = 3\), \(b = -12\).
2. Apply vertex formula: \(x = \frac{-(-12)}{2*3} = 2\).
3. Find y-coordinate: \(f(2) = 3(2^2) - 12(2) + 1 = -11\).
So, the vertex is at \((2, -11)\).