Chapter 3: Problem 61
61–68 ? Determine whether the function f is even, odd, or neither. If f is even or odd, use symmetry to sketch its graph. $$f(x) = x^2$$
Short Answer
Expert verified
The function \(f(x) = x^2\) is even and symmetric around the y-axis.
Step by step solution
01
Understanding Even Functions
A function is called even if, for every value of \(x\) in the domain of the function, \(f(-x) = f(x)\). Even functions have symmetry around the y-axis.
02
Calculate f(-x)
For the function \(f(x) = x^2\), substitute \(-x\) in place of \(x\) to find \(f(-x)\). We have \(f(-x) = (-x)^2\). Since squaring a negative number results in a positive number, \((-x)^2 = x^2\).
03
Comparing f(x) and f(-x)
With \(f(x) = x^2\) and \(f(-x) = x^2\), it is evident that \(f(-x) = f(x)\) for all \(x\). This satisfies the condition for even functions.
04
Conclusion About Symmetry
Since \(f(x) = x^2\) meets the condition for an even function, it is symmetric around the y-axis. Graphically, when you plot the function, for every point \((x, f(x))\), there exists a corresponding point \((-x, f(x))\) making it symmetric.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Function Symmetry
Symmetry in functions is a fascinating topic because it helps us understand how a graph behaves across certain axes. When dealing with functions, symmetry plays a key role in simplifying their analysis.
There are different types of symmetry:
There are different types of symmetry:
- Y-Axis Symmetry: If a function is described as even, it has y-axis symmetry. This means that if you "fold" the graph along the y-axis, both sides will match perfectly.
- Origin Symmetry: Associated with odd functions, this symmetry means rotating the graph 180 degrees around the origin will result in the same graph.
- If a function is even, then for all values of x, the equation \(f(-x) = f(x)\) holds true.
- If a function is odd, you will find that \(f(-x) = -f(x)\).
Parabola Graph
When you think of a parabola, imagine the smooth, U-shaped curve that is a hallmark of quadratic functions, such as our function \(f(x) = x^2\). Parabolas are the graphs of quadratic equations, and they have some distinct characteristics:
- Vertex: The turning point of the parabola. In the case of \(f(x) = x^2\), this is at the origin (0,0).
- Axis of Symmetry: Parabolas have a vertical line running through the vertex which divides the graph into two mirror images. For \(f(x) = x^2\), this is the line \(x = 0\), or the y-axis.
- Opening: Parabolas can open upwards or downwards. In an equation like \(f(x) = x^2\), the curve opens upwards.
Even and Odd Functions
Functions are classified into two categories based on their symmetry properties: even and odd. Understanding their characteristics helps you determine the shape and balance of their graphs.
- Even Functions: As previously mentioned, even functions satisfy the condition \(f(-x) = f(x)\). Their graphs are symmetric about the y-axis, which means that they provide a mirrored view on either side of this axis.
- Odd Functions: If a function fulfills \(f(-x) = -f(x)\), it's classified as an odd function. The graph of an odd function will look the same after a 180-degree rotation around the origin, showcasing symmetry about the origin.
- Neither: Some functions do not meet the criteria for being even or odd, so they lack those specific types of symmetry.