Question

Determine which relation is a function.

Answer 1

In a function, x values will never repeat.

Answer 2

There will only be one output for each input.

Answer 3

All the coords look like they are on both x and y axis'

Answer 4

The only one I can sort of see correct is B...

Answer 5

It's not x-intercept it's just general x value. The wrong ones have points on the same x value. For isntance, in B, two points share the x value of positive 2.

Answer 6

Hmm, okay.

Answer 7

That's the key, if you see a vertical line like that with two points, it has more than one x value making it not a function.

Answer 8

It can't be slanted, either?

Answer 9

Just vertical lines. Look at each graph and see if two points are on the same vertical line, which means they share x values.

Answer 10

I don't really see any other vertical lines. Just slanted ones now. But at least we ruled out B.

Answer 11

I don't think you understand. Look at the points.

Answer 12

Take the first line. I drew a red line through them because they form a vertical line. If you type out the coordinates it makes sense

(-2, 1)
(-2, -2)

They share an x of -2

Answer 13

And the second red line as well

(2, 0)
(2, -2)

they share an x value of 2

functions will not repeat x values

Answer 14

Well, I'm still not sure about this. But maybe this could help you to help me. This is how I look at the options.

Answer 15

dont draw slanted lines, only draw vertical lines

Answer 16

vertical lines = x values

Answer 17

The only vertical line I see are for B and C. The only difference between the both of them is that B has two vertical lines and C has one. Although, I am now realizing that C could be the answer that matches what you told me.

Answer 18

Any vertical lines means its not a function. They don't repeat x values so vertical lines automatically rule out.

Answer 19

Oh. ._. I see. So now that leaves us with just A and D. A seems like a reasonable answer because they are showing two slanted lines.

Answer 20

Slanted lines dont amtter. Only verticals. We are focusing purely on verticals.

Let me explain it:

x = 2

This expression means ALL VALUES with a value of x. This make a vertical line on the x-axis on 2. The line has all values that have 2 as their x-coordinate.

Answer 21

Remember what I said: Functions NEVER repeat x values, which is why vertical lines are so important to understand

Answer 22

But I thought we were ruling out vertical lines. "Any vertical lines means its not a function. They don't repeat x values so vertical lines automatically rule out." I must have interpreted this wrong, then.

Answer 23

Exactly. Any poitns on the vertical line means it has that x-value. If there is a vertical line which contains MORE THAN 1 POINT it means its not a function.

Answer 24

which is why this is so important to look at

Answer 25

But we were only ruling out the vertical lines. That's why I thought A was a good option, because on option A, they were only slanted/diagonal lines.

Answer 26

Ok listen, the slanted lines literally mean nothing and are not important. Look at each graph. Points that lie on the same x value (vertical) make it not a function

Answer 27

Ok, got it.

Answer 28

So, basically we need to find x=-2 stuff...

Answer 29

x = anything

anything that shares x value makes it so that its not a function

its no that hard to understand

Answer 30

Maybe I'm just thinking about it too hardly. Give me a minute.

Answer 31

yeah its pretty simple dont complicate urself

Answer 32

sorry if i come off a bit grumpy, its 11 pm over here xD

Answer 33

Oh, okay...I totally understand. It's 7:51PM over here. Sorry if I'm taking a long time to understand it. Then I'd narrow my options down to B and C.

Answer 34

Those are the ones we ruled out because there are points that >>share x-values<<

Answer 35

Okay, then I rule out D too.

Answer 36

woops, caps