Tuesday 28 August 2012

definition of a function

In the previous post we have discussed about How to Find the Domain of a Function and In today's session we are going to discuss about definition of a function. In this blog we will discuss the definition of a function. Function is used to show relationship among set of inputs and set of outputs in which every value of input is related to exactly one value of output. In other words a relation defined from I to J such that a sub set of I * J is called as function from I to J. Let's us understand the concept of function and its types. There are different types of function which are given as:
One – one function
Many one function
Onto function
Now we will have small introduction about all its types.

One – one function (it is also called as injection function): - A function f: I → J is said to be one – one function if every input value of element 'I' has different image in 'J'. So it can be written as:
f : I → J is one – one if value of 'i' not equal to 'j'. (i ≠ j) → f (i) ≠ f (j) for all ij Ԑ I.

Many one function: - A function f :I → J is said to be many one function if two or more elements of set 'I' have same images in 'J'. In mathematical form it can be written as:
f: I → J is a many one function if there exist a, b Ԑ I such that a ≠ b but f (a) = f (b).

Onto function: - A function f: I → J is said to be onto function or it is also said to be 'surjection' if every value of element 'J' is image of some element of 'I' that is if f (I) = J, and range of 'f' is co – domain of function 'f' or in other words elements of 'J' has no pre – image in element 'I'. This is all about types of functions.

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Monday 6 August 2012

How to Find the Domain of a Function

Hello friends, in mathematics we will study about the range and domain of function. Here we will discuss how to find the domain of a function. Function can be defined as a tool used to demonstrate the relationship between values. Now we will see how to find the domain of a function. Generally, functions are defined as f (p) where ‘p’ is the value you assign it. Like, f (p) = p / 2 ('f' of 'p' is divided by 2) is a function, because for every value of 'p' you get another value 'p / 2. If we put different values of function 'p'. First of all if we put value of 'p' as 2 then we get:
⇒f (2) = 1,
⇒f (4) = 2.
To find domain of function it is necessary to learn what the domain of a function is. When we select the entire x - coordinates values in the given function, then these x- coordinates values are known as domain of a function. In same way, the possible ‘y’ coordinate values are said to be the range of a function. Suppose we have some values (6, -5), (-9, 4), (11, -9), (-15, 1), then domain of function can be found as:
The domain of a given function = 6, -9, 11, -15.
Range is all ‘y’ coordinate values, (know more about Domain of a function, here)
Range = -5, 4, -9, 1. Now we will discuss how to find domain of a function in details. We need to follow some steps to find domain of a function:
Step 1: First of all we have to assume a function that contains ‘x’ and ‘y’ coordinates.
Step 2: As we know the domain of a function is all ‘x’ coordinates values.
So, we can say that in a function if values of ‘x’ and ‘y’ coordinates are known then we can easily find the domain and range of a function. This is all about the domain of a function.
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