Question

I really dont understand




Which relation is a function?

A.
{(0, 3), (0, 9), (12, –4)}

B.
{–2, 10), (–6, 10), (–2, 3)}

C.
{(5, 5), (5, 9), (5, 15)}

D.
{(–5, 1), (4, 9), (6, 10)}

Answer 1

A function is where one x-value only corresponds to one y-value

Answer 2

(not vice versa)

Answer 3

i knew that thank you though, but what i dont understand is how would i find the answer to this?

Answer 4

For example, in B, -2 corresponds to both 10 and 3

Answer 5

Which makes it NOT a function

Answer 6

Think of it this way: if you could make a list of every possible x value, and next to each x value you had just 1 y value, so even the least mathematically skilled person could look at the value of x and give you the corresponding value of y, it's a function. If they have to make any decisions at all, it's a relation, but not a function :-)

Answer 7

so it would either be C or D?

Answer 8

Let's make the list for C:

x y
5 5, 9, 15

"Mr. Doofus, my ticket has a 5 on it, which room do I go to?"
"Uh, gee, I don't know, it could be room 5, or room 9, or room 15"

Not a function...

For D:

x y
-5 1
4 9
6 10

"Mr. Doofus, my ticket has a -5 on it, which room do I go to?"
"It says here go to room 1"

Mr. Doofus, my ticket has a 4 on it, which room do I go to?
It says here go to room 9

Mr. Doofus, my ticket has a 6 on it, which room do I go to?
It says here go to room 10

D is a function, no decision-making required.

Answer 9

With a function, if you know the value of \(x\), that means you know the value of \(y\), every time. There's some rule or table to convert the value of \(x\) into its corresponding value of \(y\). You could describe the graph by just listing all the values of \(x\) that you use, and someone in possession of the function rule or table could reconstruct the graph with 100% accuracy.

On the other hand, if you got to choose from a couple of different \(y\) values for any given \(x\) value, they would not be able to reproduce your graph without knowing which decision you made at each point where multiple \(y\) values correspond to a single \(x\) value.

Answer 10

Imagine a set of driving directions:

"Drive 3 miles. When you see a red house, turn left. Drive 2 miles. Stop at the 3rd house on the left."

That's a function.

"Drive 3 miles. When you see a red house, either turn left or right or go straight. Drive 2 miles. Stop at the 3rd house, pick whichever side of the street you like."

That's not a function.

Answer 11

oh okay

Answer 12

can you help me witb one more please?

Answer 13

with

Answer 14

let's see it...

Answer 15

Which relation is a function?


A. http://static.k12.com/calms_media/media/243500_244000/243574/1/d8e4b88b7621d157ab5cb490a53c000b4dcd7de2/VHS_PA_S2_02_L211_L310_Q5b.gif


B. http://static.k12.com/calms_media/media/243500_244000/243576/1/00e1d0d64078d4605851b109858d13863e53c2fd/VHS_PA_S2_02_L211_L310_Q5d.gif


C. http://static.k12.com/calms_media/media/243500_244000/243573/1/2c3a4d37f90a3fd6674b62941dc5af943fefec9b/VHS_PA_S2_02_L211_L310_Q5a.gif


D. http://static.k12.com/calms_media/media/243500_244000/243575/1/337112bd131f723896dd8d910f232a787d41c6e1/VHS_PA_S2_02_L211_L310_Q5c.gif

Answer 16

Does the x and y correspond to each other? I mean does it contain any pattern?

Answer 17

Another way to check for function-hood is called the vertical line test. If there is any point on your graph where you can draw a vertical line and have it intersect more than one point on the graph, you do not have a function.

Answer 18

For example, graph A has a point at \((3,3)\) and \((3,-3)\). A vertical line at \(x=3\) would pass through both points, so it fails the vertical line test.