Maxima and Minima of a function

In summary, there are a few different ways to find minima and maxima for functions, such as using the Derivative Test or completing the square for quadratic functions. However, for more complex functions, it may be difficult to find an exact solution and instead, estimation may be necessary.
  • #1
n0_3sc
243
1
Are there any analytical techniques to do this besides the Derivative Test?
 
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  • #2
There is no general method except by checking where the derivitive is 0 (or does not exist). For some functions, there are other ways. For example we can always find minima and maxima for quadratic functions by completing the square.
 
  • #3
I see. Thanks for that.
 
  • #4
But there is also possibility to estimate. If you solve some elementary function, for example:
[tex]f(x)=x^2+3x+2[/tex]
You can transform it to form:
[tex]f(x)+\frac{1}{4}=\left(x+\frac{3}{2}\right)^2[/tex]
So now you are able to find a minimum:
[tex]\min_{x\in\mathbb{R}}f(x)=-\frac{1}{4}[/tex]
 
  • #5
Yes, but my function is far too complex/tedious to do either way. An expression for the min and max has been found though proving it is too difficult for me.
 
  • #6
lukaszh said:
But there is also possibility to estimate. If you solve some elementary function, for example:
[tex]f(x)=x^2+3x+2[/tex]
You can transform it to form:
[tex]f(x)+\frac{1}{4}=\left(x+\frac{3}{2}\right)^2[/tex]
So now you are able to find a minimum:
[tex]\min_{x\in\mathbb{R}}f(x)=-\frac{1}{4}[/tex]

Well if you are working with quadratics a lot you should know that the min/max is going to be at [tex] \left(\frac{-b}{2a}, f\left(\frac{-b}{2a}\right)\right)[/tex]
 

1. What is the definition of a maximum and minimum of a function?

A maximum of a function is the highest point on the graph of the function, while a minimum is the lowest point. They are also known as the global maximum and minimum, as they are the largest and smallest values of the function over its entire domain.

2. How do you identify the maximum and minimum of a function?

To identify the maximum and minimum of a function, you can use the first and second derivative tests. The first derivative test involves finding the critical points (where the derivative is equal to 0 or undefined) and checking if the derivative changes sign at those points. If the derivative changes from positive to negative, the point is a maximum, and if it changes from negative to positive, it is a minimum. The second derivative test involves evaluating the second derivative at the critical points, and if it is positive, the point is a minimum, and if it is negative, it is a maximum.

3. Can a function have multiple maximum or minimum points?

Yes, a function can have multiple maximum or minimum points. These are known as local maximum and minimum points. They are the highest and lowest points in a specific interval, but not necessarily the overall highest or lowest values of the function.

4. How do you find the absolute maximum and minimum of a function?

The absolute maximum and minimum of a function can be found by evaluating the function at the endpoints of its domain and at the critical points. The largest and smallest values obtained from these evaluations will be the absolute maximum and minimum of the function.

5. Can a function have a maximum or minimum at the endpoints of its domain?

Yes, a function can have a maximum or minimum at the endpoints of its domain. This occurs when the function is only defined on a closed interval, and the highest or lowest value of the function is at one of the endpoints.

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