In maths, what is a function?

Question

I just need a plain english explanation of what a function is in maths.

Answer 1

Here's a link from a college that allows it use to the public...I'm a math tutor...as you see on this link..it will show you all the different types of functions and what they represent...a function is basically related to the term of operations....

http://www.ltcconline.net/greenl/courses/154/systfunc/funalg.htm

Answer 2

Let A, B be two sets. A function f is a rule that associates a unique element y in B to each element x in A. We may rephrase it and say that a function maps into a single element y in B every element x in A. We could also say that for each x in A f maps x in an element y of B such that to each x there exists only one y in B such that f(x)=y.

In simple words: a function can be a rule, a grid, a table or anything that let me associate to each x in A a determined element y in B. We will also say that y is the image of x.

Functions can also be called applications or mappings. There are some basic characteristics that a function may have.
A function f is said to be iniective if whenever x and x' are two dinstinct elements of A, then f(x) and f(x') are two distinct elements of B. In words: each value is mapped in a different value.
A function f is said to be surjective if for all y in B there exists x in A such that f(x)=y. We may rephrase it in this way: a function is said to be surjective if Im(f)=B (that is, f(A)=B).
A function f is said to be bijective if it is both iniective and surjective.

Answer 3

A function is simply a formula, specifically a formula that relates two or more things.
Here is an example.
The two things in this case will be "allowance" and "chores"
The formula for your allowance is the number of chores you do each week, times 50 cents.
This is a function that relates the effort you put out to the amount of money you get.
This "function" can be written Allowance = N * .5
where N is the number of chores you do, and .5 is the half-dollar per chore.

Here is another example:
You can run TWICE as fast as your brother. The two "things" are "your speed" and "our brother's speed".
your speed = your brother's speed * 2

most functions are expressed using smaller "descriptions", so if you change "your speed" to G and "your brother's speed" to B, then the function
G = b*2 is a more common way of writing a function.

Answer 4

well.......

In mathematics, a function relates each of its inputs to exactly one output. A standard notation for the output of the function f with the input x is f(x).

It is a usual practice in mathematics to introduce functions with temporary names like f; we might define f(x) = 2x+1, and then f(4) = 9. When a name for the function is not needed, often the form y=x2 is used.

again,The essential property of a function is that for each input there must be one unique output. But, If we use a function often, we may give it a permanent name as, for example,

square(x)=x^2


You can get the full deal here...
http://en.wikipedia.org/wiki/Function_%28mathematics%29

hope i helped.
-dawgy

Answer 5

A function is like a rule. It is usually written like an equation.
Y = mx + b
This is the general equation for a line, it is a function because for every x value that you put in the equation you will get one and only one value for y.
That is called a one-to-one function.
y = 3x + 4 is a one to one function. The x is an independent variable and the y is dependent on the x.

Answer 6

Noe of many rules followed in math. For instance, when you see the + sign, you know to ADD. ADD is the function.

There you go, plain and simple.

Cheers!

Answer 7

A function is a rule you use.
Use y=mx+b

Answer 8

If you graph your equation, and there is no point where you have more than one Y value for any given X value, you have a function.

Simply, there's no point on the graph where a piece of the line/curve is directly above another piece of the line/curve.

Answer 9

a function is a rule...or a patter... plain and simple

when tehy ask the functionof the table.. or the grid... or whatever... it is the rule/pattern they are looking for,