In differential calculus, the absolute extrema of a function is the greatest and least values of the function.

The Absolute Maxima is the point where the function reaches its maximum valueSimilarly, the Absolute Minimum is the point where the function reaches its minimum value.

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What is Absolute Maximum?

In a function or a relation, the highest point over the entire domain is defined as the Absolute Maximum. Or in other words, over its entire curve, the largest value that a function can have is called the absolute maximum. It is the peak value for which the function is valid or holds.

How do You Justify the Absolute Maximum?

On a closed interval, one has to identify all the critical values as well as the endpoints of a function. Once you identify all such points, you need to identify which value of X corresponds to Absolute maxima. In other words,

  • The absolute maxima of a function f (x) = c is f (c), where f (c) ≥f (x) for all x in the domain of f.
  • The absolute minima of a function f (x) = d is f (d), where f (d) ≤f (x) for all x the domain of f.

How do You Find the Absolute Maximum and Minimum?

Let us consider a function f(x) has intervals [a, b]. Now to find the absolute extrema of f(x) on [a, b] you have to,

  • Check whether the function is continuous on the interval [a, b]. Find out all possible critical points of the function that are on the interval [a, b].
  • Assess the function at the critical points and the endpoints. Identify the Absolute Maxima and Minima from the values.

How to Find Absolute Maximum and Minimum on a Graph?

There is a difference between locating the extreme points in a graph in an entire domain and an open interval. A two-dimensional graph has an X-axis and a Y-axis. The horizontal axis is the X-axis, while the vertical is the Y-axis. The highest and lowest point of a function f(x) in the Y-axis determines the absolute extrema of f(x). Hence, to obtain the absolute maximum and minimum we need to study the graph to see where it reaches the highest (maxima) and lowest (minima) points on the domain of the function.

How to Find Absolute Max and Min without Interval?

Suppose a function f(x) has an interval I [a, b]. If f(x) is continuous on the bounded interval [a, b] then, f attains both its absolute max and min values at [a, b]. You can find out the absolute max and min without interval [a, b],

  • Identify all the critical values. Find out the function f(x) at all critical values as well as at the two values a & b respectively.
  • The absolute max of the function f(x) will be the largest value obtained from an interval a, b from the previous step.
  • Similarly, the absolute min of the function f(x) will be the least value found on the interval a, b that is found from the second step.

How to Find Absolute Extrema from the Derivative Graph?

  • Consider a function f(x) and assume that for each value of x, we can evaluate the slope of the tangent to the graph y=f(x) at x. However, this slope depends on the evaluation of x which we choose and hence is a function in itself. So, we call this function the derivative of f(x) and represent it by f´(x). In other words, the derivative of the function, f(x) at the point x= slope of the tangent to y=f(x) at x.
  • The graph of the function y=f(x) has local maxima at the point where the graph alters from descending order. The tangent has zero slopes at this point. The graph has absolute minima at the point where the graph alters from ascending order. Similarly, the tangent has zero slopes at this point as well.

Find Absolute Max and Min Calculator

Absolute max and min calculator can be found on the Google search engine. Then, click any of your desired links and you can get a maxima and minima calculator on their website.

  • You have to input the values of all other data required to evaluate the extrema values in the calculator. For example, consider a function f(x) with an interval [a, b].
  • Now, just input the one variable function in the given column of the calculator. In other columns, there will be a space for giving the interval.
  • Provide the values of the interval [a, b] and evaluate. The calculator gives you the local extrema values correct up to four or five decimal places.

How to Find Absolute Maximum and Minimum on the Open Interval?

  • In open intervals, a continuous function is not certain to have absolute maxima or minima like that in closed intervals. Your only contenders for absolute extrema will be the relative extrema. However, you can look at the limits of the function f(x) as you reach either of the endpoints. If the limit is greater than all the relative maxima, then there are no absolute maxima. Similarly, if the limit is less than all the relative minima, then there are also no absolute minima.
  • For instance, let a function f(x) =x2−x−2 has a relative minimum when x=0.5. We know without ado that there may not be any absolute maxima. However, this relative minima is the absolute minima.

Absolute Maximum and Minimum Examples

Consider the function, f(x) = x3-6x2+9x+8. Now let us find the absolute maxima and minima values of f at the intervals [1, 8].

So, we have f(x) = x3-6x2+9x+8, where [a, b] = [1, 8],

  • In the first step, we will differentiate the function f(x) and find its first-order derivative. Let us call it f´(x).
  • So, now we got f´(x) = 3x2-12x+9 = 0, after evaluating the first order derivative.
  • In the next step, we will take 3 as common. So the equation reduces to.
  1. f´(X) = 3(X2–4x+3) = 0
  2. f´(X) = X2–4x+3 = 0
  3. f´(X) = (X–1) (X–3) = 0
  4. Or, X = 1, 3 & 8

Now we will make a table and find out the value of f(x) for interval 1. This gives the value.

● F(X) = (1)3 – 6(1)2 + 9(1) + 8 = 12

Similarly, we will make a table and find out the value of f(x) for 3. This gives the value.

● F (X) = (3)3 – 6(3) + 9(3) + 8 = 8

In the same way, we will make a table and find out the value of f(x) for 8. This gives the value.

● F (X) = (8)3 – 6(8) + 9(8) + 8 = 208

Hence, the highest value of the function f(x) is at the interval 8 and the absolute maxima is 208. Similarly, the lowest value of the function f(x) is at the interval 3 and the absolute minima is 8.

Tips

  • You can solve it in both graphical as well as analytical ways.
  • Both give you the same result.
  • In this way, you can also cross-check your problem whether you have calculated correctly.

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