I dont get functions.For example, is the expression y=5 a function or not a function??

Question

i dont know how to decide wheather one is a function or another is not a function

Answer 1

That's a valid function. For each value of x, it assigns one and only one value of y. It just so happens that this value is always 5.

Answer 2

No, that is an assignment. All cases say y will be 5. In algebraic a function is on the blackboard as:

f = x.

where x IS a function OF

In javascript code it is:

var x = 0;
function mySpiffyFunc( var y ) {

x = x+y;
}

x will now have the value of y plus the addition operation. it started out as a global variable assigned a value of 0. the function changed it.

we code the function with an example like:

var width = mySpiffyFunc( 15 );

(my code is useless. I want to demonstrate what corresponds). hope this helps.

Answer 3

5x=y is a function like f(x)=y

the definition of a function is that for each x you get only one y value

there is a vertical line test for functions, the graph cannot cross any vertical line more than once.