How to Memorize Even and Odd Functions?

In summary, even functions can be reflected in the y-axis without being changed and odd functions can be rotated 180 degrees about the origin without being changed. Polynomials that include only even or odd powers are even or odd functions, respectively, but there are also non-polynomial even or odd functions. To remember this, one can think of the letter "V" as representing an even function and use the definitions that f(-x) = f(x) for even functions and f(-x) = -f(x) for odd functions.
  • #1
basty
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How do you memorize the even and odd function?
 
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  • #2
Even functions can be reflected in the y-axis without being changed and odd functions can be rotated 180o about the origin without being changed. Is this what you're asking to try and remember?
 
  • #3
I memorize by that ##f(x)=x^n,n\in \mathbb{N}## is an odd function if ##n## is odd but is an even function if ##n## is even.
 
  • #4
tommyxu3 said:
I memorize by that ##f(x)=x^n,n\in \mathbb{N}## is an odd function if ##n## is odd but is an even function if ##n## is even.
I'm not sure what you mean you are "memorizing". It is true that a polynomial that includes only odd powers is odd and a polynomial that includes only even powers is even but there exist many even or odd functions that are not polynomials, such as cos(x) and sin(x). If you mean you are thinking of [itex]x^n[/itex] to remember the definition of "even" and "odd" functions, surely it is not that difficult to remember the definitions themselves.
 
  • #5
Yes, I know their definitions exactly, and I do just mean the memorization, for I think this may be what the starter meant.
Besides, ##f(x)=0## is also a polynomial and is both odd and even, which didn't only include odd powers, though its degree makes lots of explanations.
 
  • #6
basty said:
How do you memorize the even and odd function?
Perhaps sketch a straight line at 45° in the first quadrant. Picture that as one half of the letter V, and complete the other half of the "V" by drawing its mirror image in the y axis.

The letter "V" represents an EVEN FUNCTION.
 
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  • #7
If [itex]f(-x) = f(x)[/itex] then the function is even. If [itex]f(-x) = -f(x)[/itex] then the function is odd.

Example: [itex]f(x)=2x^4+4x^2-1[/itex] is even since [itex]f(-x) = 2(-x)^4+4(-x)^2-1 = 2x^4+4x^2-1 = f(x)[/itex].

Example: [itex]f(x)=x^3-3x[/itex] is odd since [itex]f(-x) = (-x)^3 - 3(-x) = -x^3 + 3x = -(x^3-3x) = -f(x)[/itex]

Exaple: [itex]f(x)=x^2-x[/itex] is neither even nor odd. Note that [itex]f(-x)=(-x)^2-(-x) = x^2+x[/itex] so that [itex]f(-x)\not= f(x)[/itex] (not even) and [itex]f(-x)\not=-f(x)[/itex] (not odd).
 

Related to How to Memorize Even and Odd Functions?

1. What are even and odd functions?

Even and odd functions are mathematical functions that have specific symmetry properties. Even functions are symmetric about the y-axis, meaning that if you were to fold the graph in half, one side would perfectly overlap the other. On the other hand, odd functions are symmetric about the origin, meaning that if you were to rotate the graph 180 degrees, it would look the same as the original.

2. Why is it important to be able to differentiate between even and odd functions?

Understanding even and odd functions is important in many areas of mathematics, including calculus and algebra. For example, even and odd functions have different properties when it comes to integration and differentiation, so being able to identify them can help in simplifying complex mathematical problems.

3. How can I memorize the properties of even and odd functions?

One way to memorize the properties of even and odd functions is to use visual aids, such as graphs or diagrams, to help you understand the symmetry of these functions. Additionally, practicing with different examples and understanding the definitions of even and odd functions can also aid in memorization.

4. Can I use any tricks or mnemonics to remember even and odd functions?

Yes, there are a few tricks and mnemonics that can help in remembering the properties of even and odd functions. For example, you can remember that the graph of an even function has symmetry about the y-axis because "even" has the letter "v" in it, which can be thought of as a reflection. Similarly, you can remember that the graph of an odd function has symmetry about the origin because "odd" has the letter "o" in it, which can be thought of as a rotation.

5. How can I apply my knowledge of even and odd functions in real-life situations?

Even and odd functions can be found in many real-life situations, such as in physics and engineering. For example, even functions can be used to describe the motion of a pendulum, while odd functions can be used to describe the position of a particle undergoing simple harmonic motion. Additionally, understanding even and odd functions can also help in solving practical problems, such as finding the maximum or minimum value of a function.

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