Showing posts with label Functions. Show all posts
Showing posts with label Functions. Show all posts

Friday, December 28

Smoothing Function in Math

Introduction for smoothing function in math:

In smoothing function in math, let f(x) be a real-valued function of a real variable x and let a be some fixed point in the domain of f. The number L is the limit of f (x) as x approaches a if, given any positive number `epsi`, we can find a positive number `delta` such that f (x) is in the range

|f(x) – L| `<` `epsi`

Whenever x is in the domain

0 `<` |x – a| `<` `delta`

We write

`^lim_(x -> a)` f(x) `=` L

More about for Smoothing Function in Math:

In smoothing function in math, the notation

`^lim_(x -> a)` f(x) `=` L

is read “the limit of F(x) as x approaches a is L.

f(x) `->` L  as x `->`a;

This is read as “f(x) approaches L as x approaches a” or “f(x) goes to L as x goes to a”. I like to explain limits by writing

f(x) `~~` L when x `~~`a (but x `!=` a).

The notation A `~~` B means A is approximately equal to B. In ? We will study a limit

f’(a) `=` `^lim_(x -> a)` `(f(x)-f(a))/(x-a)`

called the derivative. The derivative is a limit, but the concept of limit is more general. Note that in the definition of limit we consider values of x close to a but never plug in x = a. In the interesting examples (like the derivative) setting x = a in f(x) leads to something undefined like `0/0` for smoothing function in math. Is this topic 8th grade math practice problems hard for you? Watch out for my coming posts.

Example for Smoothing Function in Math:

In smoothing function in math,

`^lim_(x -> 1)` 4x `-` 2 `=` 2

`^lim_(x -> 1)` `x^2` `+` 3 `=` 12

Some limits are more difficult to find if they contain a denominator that goes to zero as x `->` a. These limits must be treated carefully using, for example, L Hopitals rule.

Proof that a limit exists requires manipulation of inequalities to determine the relationship between `epsi` and `delte`. It is also necessary to verify that the inequalities |f(x) `-` L| `<` `epsi` and 0 `<` |x `-` a| `<` `delta` are satisfied as required by the definition of a limit.

Suppose we have the limits

`^lim_(x -> a)` f(x) `=` L

And

`^lim_(x -> a)` g(x) `=` M

Then

`^lim_(x -> a)` [ f(x) `+` g(x)] `=` L + M

That is, the limit of the sum of two functions is the sum of the limits.

`^lim_(x -> 1)` [`x^2` `+` 3 `+` 4x `-` 2 ] `=` 2 `+` 12

Answer is     `^lim_(x -> 1)` [`x^2` `+` 4x `+` 1 ] `=` 14

Friday, May 8

Question on Integrating a Given Function

Here is a Multi choice question to Evaluate function by Integration.
You can find similar set of questions at TutorVista Blogs.

Topic : Integrating a Function.

Below example will help you to identify correct choice and get reasons for, why remaining choices are incorrect.

Question : At what point in the interval [0, √3] does the function y=x2 - 1 assumes its average value.
a. -1
b. 1
c. 1.5
d. 1.7

Solution :
Choice b is correct.
Average value = 1/(√3 - 0)0∫√3 (x2 - 1)dx = 0
And x2 – 1 = 0
Therefore, y= x2 -1 assumes its average at x = 1

Choice a is incorrect as -1 is not in the interval [0, √3]

Choice c is incorrect as 1.5 does not satisfy the equation x2 -1=0

Choice d is incorrect as 1.7 does not satisfy the equation x2 -1=0


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