00:01
Okay, if a relation is a function, then it means every x value in your domain maps onto at most one element in the range.
00:13
In other words, x to y is always no choice.
00:20
The first one here, if i take this x value, for example, the y value could be this number or this number.
00:29
There are two choices for the x value therefore is not a function and basically what you do with graphs is you draw straight lines on the graph that are vertical and if the vertical line cuts the graph more than once in any location is not a function so here if i draw lines that are vertical over here it cuts nowhere that's fine but here it cuts twice so that means that at once is not a function.
01:08
Here though, on the right, if i draw lines that are vertical, every time i do it, it cuts only once.
01:17
So this one is yes, it's a function.
01:21
Again, because if i take any x value at random, there's no choice about the y value.
01:29
If i choose this one, the y value must be here...