Question

what is function

Answer 1

A function, in mathematics, associates one quantity, the argument of the function, also known as the input, with another quantity, the value of the function, also known as the output.

Answer 2

Further reading:
http://en.wikipedia.org/wiki/Function_(mathematics)

Answer 3

do not get

Answer 4

i mean like how do i tell if a relation is a function?

Answer 5

If you look at a graph of it, and you can draw a vertical line anywhere on the graph without it touching two points

Answer 6

Meaning for every x-value there is exactly one y-value