Chapter 5: Problem 8
For the following exercises, rewrite the quadratic functions in standard form and give the vertex. $$ f(x)=x^{2}-x $$
Short Answer
Expert verified
The function in standard form is \( f(x) = x^2 - x + 0 \) with vertex \( \left( \frac{1}{2}, -\frac{1}{4} \right) \).
Step by step solution
01
Identify the Standard Form
The standard form of a quadratic function is \( f(x) = ax^2 + bx + c \). Given the function is \( f(x) = x^2 - x \), it can be written in standard form as \( f(x) = 1x^2 - 1x + 0 \), where \( a = 1 \), \( b = -1 \), and \( c = 0 \).
02
Determine the Vertex Formula
The vertex of a parabola in standard form can be found using the vertex formula \( x = -\frac{b}{2a} \). In this function, \( a = 1 \) and \( b = -1 \).
03
Calculate the Vertex x-coordinate
Substitute \( a \) and \( b \) into the vertex formula: \( x = -\frac{-1}{2 \times 1} = \frac{1}{2} \).
04
Calculate the Vertex y-coordinate
To find the y-coordinate, substitute the x-value \( x = \frac{1}{2} \) back into the function: \( f\left(\frac{1}{2}\right) = \left(\frac{1}{2}\right)^2 - \left(\frac{1}{2}\right) = \frac{1}{4} - \frac{1}{2} = -\frac{1}{4} \).
05
State the Vertex Coordinates
The vertex of the function \( f(x) = x^2 - x \) is \( \left( \frac{1}{2}, -\frac{1}{4} \right) \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Vertex of a Parabola
In the world of quadratic functions, the vertex of a parabola is a very important point. It is the topmost or bottommost point of the graph, depending on its orientation. If a parabola opens upwards, the vertex is the lowest point. If it opens downwards, the vertex becomes the highest point. In the function given, which is in the form of a parabola, finding the vertex will help us understand its shape and position on the plane.
Here's how it helps:
Here's how it helps:
- The vertex tells us about the function's minimum or maximum value, depending on whether the parabola opens upwards or downwards.
- It's critical in understanding the direction and steepness of the parabola.
- You can identify symmetry around the vertex, meaning both sides of the parabola mirror each other.
Standard Form of Quadratic Equation
The standard form of a quadratic equation is a common way to express a quadratic function. It's usually written as \( f(x) = ax^2 + bx + c \). This form is useful for easily identifying the coefficients \( a \), \( b \), and \( c \) of a quadratic function. In our exercise, the given function \( f(x) = x^2 - x \) was rewritten as \( f(x) = 1x^2 - 1x + 0 \). Here, \( a = 1 \), \( b = -1 \), and \( c = 0 \).
This form helps:
This form helps:
- Provide a clear method for finding the function's intercepts.
- Identify the direction in which the parabola opens by looking at the sign of \( a \). A positive \( a \) means it opens upwards, and a negative \( a \) means it opens downwards.
- Make it easier to apply the vertex formula.
Vertex Formula
The vertex formula is a formula that helps calculate the vertex's x-coordinate from the quadratic equation in standard form. The formula is \( x = -\frac{b}{2a} \). Once you find the x-coordinate, you can plug it back into the original function to find the y-coordinate, thus determining the vertex as a point \((x, y)\).
For the quadratic function in our exercise:1. We used the coefficients \( a = 1 \) and \( b = -1 \) to find the x-coordinate as \( x = \frac{1}{2} \).2. Substituting \( x = \frac{1}{2} \) back into the original function gave us the y-coordinate \( y = -\frac{1}{4} \).By completing these steps, we precisely locate the vertex \( \left( \frac{1}{2}, -\frac{1}{4} \right) \), giving us both its x and y positions. The vertex formula is an essential part of dealing with quadratic functions because it uniquely identifies the central turning point of a parabola.
For the quadratic function in our exercise:1. We used the coefficients \( a = 1 \) and \( b = -1 \) to find the x-coordinate as \( x = \frac{1}{2} \).2. Substituting \( x = \frac{1}{2} \) back into the original function gave us the y-coordinate \( y = -\frac{1}{4} \).By completing these steps, we precisely locate the vertex \( \left( \frac{1}{2}, -\frac{1}{4} \right) \), giving us both its x and y positions. The vertex formula is an essential part of dealing with quadratic functions because it uniquely identifies the central turning point of a parabola.