Question
Thu June 21, 2012 By: Muskan
i saw ur functions video and i dont like it at all because i cant understand it properly, i need to get a clear cut idea on what are functions actually.

# i dont like or understand ur defination

Expert Reply
Fri June 22, 2012
```There are many ways to define functions, depending on how precise we
want to be, and how we are approaching the subject. But the basic idea
is simple: ```
`A function is something that takes some sort of "input" and for each possible `
`input produces some "output." `
`For example, any algebraic expression involving one or more variables can be `
```seen as a function; for any set of values of the variables, the expression produces a
single value. This expression is a function of a single variable x:

3x - 1

We can explicitly call this a function by naming it (I'll call it "L"
just to be different) and defining the value of the function for any
input. We do this by stating that its value for any value of the input
is the value of our expression when x has that value:

L(x) = 3x - 1

This says that for any value of the variable x (the input), the value
of the function (the output) is 3 times x, minus 1.

You don't have to use an expression like this to define a function;
any description of how to get the output from the input will work. But
this is the usual way you will see functions defined.```
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